SUNSfan's Aghs Power Ranking v6.88

I've been having trouble figuring out what I want to write on this site. What I do know is that I'd like to keep it as a personal blog that mostly relates to Dota 2. I've considered writing about a few controversial topics, but I just haven't had enough time to flesh them out in order to do them justice.

So as a result, I thought it would be fun to write something completely brain-dead. If any of you have followed me in the past, whether it be via casting or any series I'm a part of, I always refer to the strength of an Aghanim's for a specific hero as being a "top 10 aghs in the game". I've said this so many times that it has turned into a running joke. It's finally about time that I come up with my completely arbitrary ranking of the 89 Aghs in the game currently (patch 6.88f).

Feel free to disagree with everything.

Just to note that the criteria for this list is of my own design, meaning there will be flaws…many flaws. But the following is what I kept in mind, and as always there will be exceptions:

Consistency: How often is it picked up? (Weight: Medium)
Theoretical Power: How good could it potentially be? (Weight: Heavy)
Actual Power: How good is it by the numbers? (Weight: Heavy)
Fun Factor: How cool or unique is it? (Weight: Low)
Personal Bias: Go Centaur! (Weight: Infinite)

If anything is made clear by this criteria, it's that there is no such thing as a perfect system for ranking the power and potential of Aghanim's in Dota 2. Perspectives will differ on what makes a good Aghs and no one can be inherently right or wrong. If it was so black and white, I would just list all the Aghs purchased by pro players in order of frequency. But what fun would that be?

Also, just because a hero picks up Aghanim's every game, it doesn't necessarily mean it is strong in comparison to every other upgrade in the game. Sometimes those heroes don't have a better option.

It's pretty obvious that Icefrog (and the beta testers) not only want an Aghanim's upgrade for every hero in the game, but in addition, want them to be viable in some way. This, however, doesn't mean they want all of them to have the same ceiling. The variety in power level is what makes the game fun after all.

Keep in mind that most Aghs upgrades are actually quite good. It was difficult to rank them since there are so many variables to take into account. The beautiful thing about Dota is there are an infinite amount of ways to build and play each hero, and that's why making a list that everyone agrees upon would be impossible.

Lastly, I've separated these upgrades into 10 tiers. As you'll see, the tiers are not meant to be evenly distributed. They are just there to illustrate what upgrades I feel are within the same strength scale as one another. There is definitely some interchangeability here as well, so try not to obsess over the numbers.

Just remember that this is an opinion piece and was done purely for fun. I'm not claiming to be an expert of any kind; I just really like Aghs and power rankings. All in all, there is no such thing as a consensus with things of this nature, and at the end of the day, this is not a perfect list. With the feedback of the community I'd like to update this as time goes on.

Note: Each rank has a dropdown that explains my rationale.

PS: Special thanks to Sajedene for the graphics & bukka for setting up the article.

Changelog:

1.0 - Released

1.1 -
LC - nerfed to 9th Tier
Sven - Lowered in ranking a bit
Venomancer - buffed to 6th tier
Silencer - nerfed to 8th tier
Oracle - nerfed in ranking a bit
Techies - buffed to 6th tier (I feel dirty)
Meepo - buffed to 3rd tier
Invoker - buffed to 3rd tier

Tier 10: US West Pubs (Complete Dumpster)

89
Outworld Devourer
Sanity's Eclipse
Will cast Astral on affected heroes
I think they actually forgot to update his Aghs upgrade when they changed Astral Imprisonment to not steal intelligence. On some level it could be OK since it technically deals damage, but I'm sorry, based on the sheer fact that Valve forgot to change this means it has to be the worst upgrade in the game.
88
Gyrocopter
Other
Adds side gunner!
Much to some player's chagrin, this isn't the worst upgrade in the game. Its close though…very close. You have to itemize the hero completely different in order to pull this off, and when I say pull this off, I really mean lose the game horribly.

Tier 9: Slacks' Career (For the Memes)

87
Tusk
New Skill
Walrus Kick
This is for the memes. Would actually be quite good if you could choose the direction in which enemies are kicked (vector targeting). This skill is probably better than ranked here, but I'm bitter that something called Walrus Kick is so damn awful.
86
Legion Commander
Duel
Longer duration. Only LC and opponent can take dmg from eachother
The previous iteration of this Aghanims was HILARIOUS (Infinite Duel until someone dies), but things like an infinite nightmare toggle just ruined all the fun. This Aghs is super situational, but mostly awful. It increases the duration of the duel from 5.5 to 8 seconds and it turns it into a true gentle...woman's duel where no damage can be taken from outside sources. This of course is a double edged sword that can be both incredible and horrendous, but mostly horrendous.
85
Zeus
Thundergod's Wrath
Increases damage
Boring. The increase in damage for each respective level is 100, and with Aghs you get a little over 200. Despite this jump, there are at least 10 other items that are better for Zeus.
84
Leshrac
Pulse Nova
Damage increase
Damage increase per level is 30. Aghs adds 60. Similar to Zeus in the fact that many other items will be far more effective.
83
Wraith King
Reincarnation
Nearby slain allies will transform into a wraith for 7 seconds
One of the biggest disappointments in Aghs history. It works thematically, but in practice is pretty bad. Let Alchemist give you the Aghs, as long as you're the last one to receive it.
82
Skywrath Mage
Mystic Flare
Increased duration (2.4 to 12) and lowers cooldown
5 second cooldown sounds cool until you realize each cast is 800 mana.
81
Jakiro
Macropyre
double cast range, double distance, more dmg, triples duration
Lasts for an eternity but still a pretty underwhelming upgrade. Can be used to pretty good effect to push out lanes though.
80
Axe
Culling Blade
Kill threshold from 400 to 550. Decrease cooldown from 55 to 6, Kill speed duration increased from 6 to 10
This is what we call a Level 4 ultimate. Generally not so good.

Tier 8: syndereN's Face (Overrated)

79
Bristleback
Nasal Goo
Goo is AoE
Sounds so cool on paper and can definitely be effective in certain games. But in practice…not so terrific unfortunately. I think this is reserved for if there is an Alchemist in the game.
78
Winter Wyvern
Arctic Burn
Arctic burn becomes togglable, removes limit on number of attacks per target
This isn't something you're going to see too often, but its not horrible. Having Arctic Burn as a toggleable ability is pretty nice actually. The cliff-walking alone is super nice. The 40 mana per second though is not so nice. The original ability lasts 6 seconds for 90 mana. The Aghs version will cost 240 for that duration.
77
Kunkka
Ghostship
Boat Drags units. Travel time reduced
I was so tempted to put this in a lower tier, but ultimately decided against it. I think its good for bad Kunkka players and bad for good ones.
76
Juggernaut
Omnislash
More slashes, decreases cooldown
This is a level 4 ultimate. Not great
75
Sven
God's Strength
Grants bonus damage to allies in AoE
If support Sven ever comes back, then this would be a great pickup. Until then it's well below average.
74
Silencer
Global Silence
Applies Arcane Curse to enemy heroes
This is a very interesting upgrade. Arcane curse being applied to all units seems a little weird at first, since they are silenced and can't cast spells anyway. But if you delve a bit deeper you will see that the curse is paused while units are silenced (other than the slow). With this in mind, casting Global Silence with Aghs will actually slow everyone by 18% (through magic immunity) and the damage per second will begin once the units are not silenced any longer. Despite this, there are more effective items for this price range
73
Beastmaster
Primal Roar
Cast range from 600 to 950. Cooldown from 70 to 45
It's hard to rate this very highly. Compared to a majority of Aghs in the game this is pretty weak-sauce. You're better off getting a Refresher.
72
Bane
Fiend's Grip
Duration from 5 to 7, damage from 215 to 270, mana drain from 5% to 10%. If enemy attacks bane, nightmares them.
An exteme luxury item for Bane, and its not bad. The nightmare mechanic is a little strange, but hey why not?
71
Earthshaker
Enchant Totem
The enchant totem leap
Adds an extra level of mobility, but still kind of a meme.

Tier 7: Bruno's Wardrobe (Flashy but All Over the Place)

70
Magnus
Empower
Aura (50% values for ranged)
Oh my. This was a tough one to rank. The potential for it is so high, but overall I think it's very lineup dependent.
69
Oracle
Purifying Flames
Faster cast point, lowers cooldown
Casting Purifying Flames in quick succession can be pretty powerful, both offensively and defensively. Aghanims is not somethign we get to see often at all, so its hard to put an exact ranking on this bad boy.
68
Doom
Doom
Longer duration, suspends duration when within range, removes positive buffs, breaks passives
How far this hero and Aghs have fallen. The 900 AoE suspension is a pretty cool idea, but I think in practice it's mostly overkill. The real benefits come from being able to break passive abilities and remove positive buffs. Its an OK upgrade,l but other items are better.
67
Razor
Eye of the Storm
Faster strike interval, can target structures
Pretty much only picked up if you really need help pushing high ground. Otherwise I think you'd be better served going for other items. Overall a decent Aghs though.
66
Tidehunter
Gush
Cast range increased, becomes AoE, Lowers cooldown
A luxury purchase on Tide for sure. This isn't too bad of an Aghanims overall though. Dealing damage, lowering armor, and slowing in a large AoE with a 7 second cooldown? Sign me up.
65
Enigma
Black Hole
Adds current level of Midnight Pulse
If you get a full 4 second Black Hole off, this will deal 21% of max HP to enemies (not including the Black Hole damage itself). Add an actual Midnight pulse and that percentage doubles. Its nice to have this option on Enigma, but much like other upgrades in this tier, there are typically more effective items to purchase.
64
Dark Seer
Wall
Illusions deal 140% damage instead of 90%
Normally there are more effective items to get in the game, but being able to create illusions that hit harder than the original source is pretty sweet.
63
Elder Titan
Earth Splitter
Longer slow, Disarms
This is an EXTREMELY long disarm. Of course most of the time you get hit by this ult, you'll probably want to try and run away anyway.
62
Lion
Finger of Death
Adds AoE, damage increase, lower cooldown, lowers mana cost
An extreme luxury item for Lion and probably a bit overrated in pubs. It is great for certain games where the AoE is important or fights are so consistent that a 20 second cooldown is necessary, but typically you can find better things to purchase on this hero.
61
Crystal Maiden
Freezing Field
Damage increase, movespeed slow % increase, Attack speed slow % increase
The damage increase is actually less than what you would expect from a Level 4 version of this skill, but you get the increase in move and attackspeed slow (30 to 50%). Pretty solid upgrade.
60
Lich
Chain Frost
Cast range increase, Infinite bounces, Damage increase, Move slow increase, Attack slow increase
This scales in similar fashion to CM's Ultimate (same jump in Attack and movespeed slow), except you get Infinite bounces
59
Viper
Viper Strike
Decrease mana cost & cooldown, Increases range
A hard upgrade to rate for me because I think its just generally bad on the hero. Other builds are just more effective. But if you take into account how it upgrades Viper Strike, then I think it is justfied to at least put it this high.
58
Puck
Dream Coil
Link break damage increase, Link Break stun increase, Coil duration increased, Link Break stun goes through spell immunity
This is a pretty underrated pickup for Puck. A lot of the numbers scale as you would expect for a Level 4 skill, but the critical change here is the coil duration (6 to 8 seconds) and the fact that breaking the link will stun through magic immunity.
57
Storm Spirit
Electric Vortex
Adds AoE
This will probably be a controversial one. Grabbing multiple heroes with a spell that has an 18 second cooldown should not be underrated . Of course, the main issue is that it is an extremely awkward item to pickup on Storm Spirit, which means it needs to be ranked lower than it's true potential.
56
Huskar
Life Break
More damage and cooldown reduction
The cooldown reduction is quite big (12 to 4 seconds) and the Damage increase is ridiculous (35% to 65%). Sometimes you just can't quite bring yourself to purchase this on Huskar, but if you look at the numbers it's pretty damn good.
55
Techies
Remote Mines & New Skill
Increase cast range, increase damage, adds Minefield sign
This essentially turns Remote mines into a level 4 skill. So its OK, but compared to other Aghs in game, not so much. Techies should still purchase this, but he's also a garbage hero, so perhaps it's best not to judge based on that. The minefield sign is a cool touch though.
54
Lifestealer
New skill
Eat teammates
Oh lord how I love this skill. Kind of awkward to build on this hero, but it can be so effective. Being able to eat someone, and then jump inside someone else means you have a 3 man gank squad at all times. Not to mention eating teammates in a fight could potentially save their life. The potential is very high for this item, but its ranked somewhat low because of the fact that you are building an Aghs...on Naix.

Tier 6: Your One 5k Friend (Pretty Solid)

53
Natures Prophet
Wrath of Nature
Increases bounces, damage, and creates treants if units are killed by it
You can probably justify this being a bit higher on the list, but I've seen so many people mis-use this Aghs that this ranking feels right to me. It is a situational item build for Natures Prophet, not an automatic. If you need to split push, then this is amazing. If you need to kill heroes, this is probably going to be awful.
52
Visage
Familiars
Summon 3rd familiar
I know many people think this should be higher and maybe they are right. I just have a hard time putting this in a higher tier when it "only" improves Visage's ult by 50%.. This is one of those examples where the item is 100% core on the hero, but not necessarily that amazing compared to the rest of the field.
51
Ogre Magi
New Skill
Unrefined Fireblast.
Should this be higher? At first glance it seems like you get a duplicate of your Fireblast skill (similar to Timbersaw Aghs). But the difference here is the manacost, which can either be crippling or a godsend, depending on the situation. It costs 60% of your current mana, meaning you will always be able to cast it. But if you have a lot of mana left, then it just destroys your mana pool entirely. Of course having half the mana cost compared to your Fireblast is pretty handy.
50
Shadow Fiend
Necromastery & Requiem
Increase max souls, Requiem returns to SF & Heals
I love this Aghanims. It allows you to deal more physical & magical damage while healing you afterwards. I think it fits more for the Euls/Blink build, which unfortunately has fallen out of favor (as has the hero itself).
49
Batrider
Flaming Lasso
100 damage per second, 400 radius for double grab
This is definitely more of a luxury pickup for Batrider, but the potential for game winning Lassos is there. And even if you don't catch 2, your lasso at least does damage now.
48
Spirit Breaker
Nether Strike
Cast range increase, Adds AoE, lowers cooldown
You typically will want to go other items on this hero, but this upgrade isn't too bad. The base range and AoE is pretty nice, but the real value comes in the drastically reduced cooldown (60 to 20 seconds).
47
Phoenix
Supernova
More attacks to destroy and can bring ally inside
This could be a game winning upgrade, or game losing. The potential is VERY high, similar to Weaver's Aghs. But there is also potential for failure. Either way I really like the concept behind this upgrade
46
Venomancer
Poison Nova
Damage increase, cooldown reduced
I should try to follow the same logic throughout. This is picked up every game (if possible) by Venomancer, similar to the way Ancient Apparition works. It also helps team-fights tremendously. Despite this, I can't justify putting this on the same level as AA, simply based on the fact that AA's anti-heal is a game-breaking mechanic
45
Lone Druid
Spirit Bear
No bear leash & bear survives if lone druid dies
This upgrade deletes the leash, essentially making the bear an additional hero. This can be super strong in the mid and late game.
44
Shadow Shaman
Mass Serpent Ward
Increased damage of wards
This upgrade comes close to doubling the damage of the Serpent Wards. In theory it should be higher on this ranking, but I don't care
43
Lina
Laguna Blade
Pure damage and goes thru spell immunity
Going through BKB means she doesn't fall off as hard in the late game. Of course she's awful right now, but I'm sure with some slight buffs she'll be in every pub game again.
42
Naga Siren
Song of Siren
Heals allies for 10% per second
Definitely not for carry Naga, but very potent if pulled off correctly. It's like healing ward on crack.
41
Omniknight
GA
Longer duration, becomes global and affects buildings
An extra fortify for buildings! Global range is pretty sick. But its too bad his ultimate doesn't heal anymore. Sorry Slacks.
40
Queen of Pain
Sonic Wave
Increases damage and lowers cooldown
Extra damage is nice, but the significant decrease in cooldown means you can spam this at will.
39
Faceless Void
Chronosphere
Decrease cooldown (100 to 60)
A simple cooldown reduction is pretty damn boring, but this is still a solid pickup since his ultimate is so critical
38
Chen
Holy Persuasion
Can take over Ancient Creeps
This used to be even better. It no longer lowers the cooldown of Hand of God, but Ancient Creeps are pretty durable and useful. Even the Triceratops...kind of.

Tier 5: Purge's Picks (Seems Good)

DISCLAIMER: Not actually approved by Purge
37
Brewmaster
Primal Split
Brewlings gain spells from regular hero
This was a hard one to rate. Nobody picks this up on Brew anymore, but its so theoretically strong that I had a hard time putting this any lower. Of course Brew really misses having plus stats on his cuddly spirits, but being able to use the spells from your main hero is so powerful. Of course a lot of it depends on how skilled you are at micro.
36
Dazzle
Weave
Radius increase, Armor per second increase
I would say this is an underrated Aghanims. The increased armor per second is nice, but the AoE increase is pretty disgusting.
35
Vengeful Spirit
Nether Swap
Cooldown reduced, creates illusion of self on death with refreshed abilities
This is something we rarely see in professional games, but it's a very high value item for Venge. I always thought this was one of the best upgrades in the game when it only changed the cooldown, which is quite significant (45 to 10). But the Venge illusion is pretty awesome too. You can't use items but every single one of your skills is off cooldown, including Nether Swap. Oh and you can now swap non-hero units for getaways. Pretty insane upgrade.
34
Tinker
Laser & Missile
Lasers bounce, and Increases missiles
This item ensures Tinker as the most annoying hero in the game. Very powerful for teamfights and high ground defense.
33
Ursa
Enrage
Cooldown reduced, allows use while disabled
When Aghanims for Ursa was first introduced, many were skeptical. But it definitely serves a worthwhile purpose on this agility hero. The cooldown reduction is great and being able to cast this while stunned can be super hard to counter. It is picked up quite often by Ursa players, but still a somewhat situational option.
32
Warlock
Chaotic Offering
Creates 2nd golem with reduced stats)
Quite a good Aghs that is picked up very often on the hero. This is simlar to AA where the hero will typically play support and buy a midas for the sole purpose of getting Aghanims at some point. Something that a lot of people overlook is that the stats of the Golems actually decrease when you get upgrade, but of course having 2 is always better than 1
31
Drow Ranger
Marksmanship
Splinter attack
Turns her into a squishy Medusa that deals dumb amounts of damage
30
Sand King
Burrowstrike
Doubles cast range and travel distances. Caustic finale is added to heroes stunned
It is almost like having a second blink
29
Shadow Demon
Demonic Purge
3 charges with 40 second replenish time. Breaks passives
Hard to get for SD, but very powerful. The passive break is somewhat situational but still incrediblely good.
28
Clockwerk
Hookshot
Cooldown from 40 to 12
Boring on paper but the low cooldown makes such a huge difference for this hero
27
Witch Doctor
Death Ward
Bounces up to 4 times
Turns a decent ultimate into an incredible one. You could make the argument that this should be higher, but his ult can be inconsistent at times.
26
Abaddon
Borrowed Time
plus 1 sec duration & 50% redirect dmg
This was a very difficult one to rank. In theory I think this could be significantly higher but I feel like even if it is picked up by Abaddon (which is rare), it is somewhat inconsistent. But the theoretical power is so high with this item that I would feel remiss not to include it in this tier.
25
Windranger
Focus Fire
No damage reduction, reduces cooldown, removes penalty from Unique Attack Modifiers
This pretty much brings the Windrunner carry online. Quite a good pickup.
24
Morphling
Hybrid
Hybrid Ability. Creates a replicate of a target hero, which can cast all non-ultimate abilities
Forget what hero this is for and read the description of Hybrid. You create a version of an allied hero, which can use every non-ultimate ability. You take normal damage and deal 50% damage. In certain lineups this is disgustingly good. By this description alone, I would say this has potential to be a top 5 Aghs in the game, but the fact that it's on Morphling means we have to dock some points away. I suppose a support Morph can pull this off, but that isn't exactly a thing these days. Either way it's a very interesting upgrade and I hope we see more of it in the future.

Tier 4: Envy's Blog (Powerful)

23
Disruptor
Static Storm
Dmg increase, duration increase, mutes items
The only other skill that can mute items is Doom. And this one is AoE. Not bad! It isn't something we get to see too often, but I think the potential for this one is very high and changes the complexion of the game.
22
Pudge
Meat Hook
Increases damage and lowers cooldown
The damage increase is nice, but the cooldown reduction is where its at (11 to 4 seconds). Relocating enemy heroes is a pretty powerful ability. Being able to do that on a constant basis is scary for the opposing team. Throwing out random hooks has never been so fun.
21
Undying
Decay
Strength steal increase
This is the dream for any Undying player. Of course, its not always realistic to purchase unfortunately. But if you DO get it, you steal 10 strength per decay. Thats 200 HP you gain from a shitty 1 man decay. Imagine if you get a 5 man decay. That's 1000 HP!
20
Enchantress
Impetus
Attack Range increase
A very unique upgrade that obviously synergizes perfectly with her ult. Add this in the mix with Dragon Lance and you're suddenly a carry.
19
Bloodseeker
Rupture
2 charges. 40 second replenish time (instead of 60 sec cooldown)
Started as a meme, but as become more of a norm in the past few weeks. It's extremely strong. In many fights you'll find you have time to cast a third rupture which is insane.
18
Pugna
Life Drain
Increases damage and lowers cooldown to 0
A forgotten hero, but an amazing Aghs. 0 cooldown & increased damage is a bit boring in concept, but it works so damn well. Now saving someone, killing illusions, or using it as normal becomes so much stronger.
17
Ancient Apparition
Ice Blast
10 sec duration to 17
The one required item on any Ancient Apparition. It changes the game completely when picked up.Teams are usually hesitant to fight when they are hit by a regular Ice Blast, but with the extra 7 seconds, it makes it almost impossible.
16
Timbersaw
New Skill
Second Chakram
Gives you a second Chakram. As if Timbersaw didn't have enough burst damage
15
Mirana
Starstorm
Adds passive Starstorm
Gives you a second starstorm for free and with a shorter cooldown than the original! Not bad. It has turned her into a completely different hero, but it seems to be for the better.
14
Weaver
Time Lapse
Reduces cooldown, Can cast on allies
It may seem awkward on the hero, but support Weaver is quickly turning into a thing. Either way, this ability is WAY too strong to use on other heroes to not be this high on the list. Especially considering the cooldown gets reduced from 40 seconds to a ridonkulous 16!
13
Luna
Eclipse
Creates huge cast range, increases beams, no limit per unit, shorter interval. Can cast AoE or on other units
People thought this was a meme build, but we've seen it work on countless occasions. Being able to cast this in an AoE or on an intiation hero is incredible. Also, removing the beam limit per enemy makes this one of the highest damage output spells in the game.
12
Treant Protector
Overgrowth & New Skill
Eyes in the forest. Overgrowth does damage when enemies are near an Eye
One thing is clear here. Icefrog really wants Treant protector to have eyes in the forest. They have tried so many times to give him an ability similar to this (dota 1), but it never quite worked out. So it only makes sense that they bring it to his Aghs upgrade. Treant is already considered a mobile ward with his Nature's Guise ability. Eyes of the forest takes this to the next level.
11
Tiny
Grow
Toss dmg increase, Attack range increase, Cleave, Bonus dmg to buildings
This makes you a building destroyer and farming machine. A very unique Aghs that changes the game when it is picked up.
10
Rubick
Spell Steal
Cast range increase, lowers cooldown, and upgrades spells
Similar to the Invoker Aghs, on paper this may seem a little boring but the cooldown decrease is more than significant. We're talking about going from 16 seconds to 2! Also being able to steal an Aghanim's skill from an enemy that can't even afford the item themselves makes the potential of this upgrade for Rubick off the charts

Tier 3: Puppey's Headset (Game Breaking)

9
Meepo
Divided We Stand
Adds another Meepo, increases shared attribute percentage
The benefit of an extra Meepo is obvious. You get an extra Earthbind, Poof, and right clicker. But what makes this upgrade so good is that attribute bonuses from items are shared to all Meepos. Gogo triple Dragon Lance build.
8
Invoker
Invoke
Reduces cooldown & 0 manacost. Adds one level to the stats provided by Quas, Wex, and Exort on all Invoked spells.
On paper this is a very boring upgrade as it's simply a manacost and cooldown decrease, along with adding one level of stats to all spells. But of course it becomes a lot less boring when you're talking about a hero with 10 spells that he can easily spam with this upgrade.
7
Centaur Warrunner
Stampede
60% damage reduction, terrain walking
I love Centaur. Does that make me biased? Yes. But I still think this Aghanim's upgrade is amazing. Being able to reduce 60% of damage for your entire team (globally) is game winning. The icing on this delicious Centaur cake is that they can all run through cliffs and trees as well.
6
Earth Spirit
Grip & New Skill
Grants the Enchant Remnant ability. Also allows grip to pull allied heroes
This was quite hard to rate as you don't get to see it all too often. Let's break this up a bit. Firstly, remember when Earth Spirit was completely overpowered? The main reason for this was his ability to use Geomagnetic Grip on allies. They got rid of that functionality and added it for when you get Aghanims. Its a 13 second cooldown spell that can save allies VERY consistently. Next, this upgrade gives Earth Spirit a new skill that can turn allies or enmies into a stone, which he can manipulate in any way. This is a very strong ability in the right hands.
5
Keeper of the Light
Illuminate & Spirit Form
Constant Spirit Form, Illuminate Heals during day
Shoutout to syndereN on this one. This is an insane upgrade. It permanantly gives you Spirit Form, which means you will forever have 2 skills (Recall & Blinding Light). In addition you will receive clear vision during the day and your Illuminate will heal during the day.
4
Necrophos
Reaper's Scythe
Damage increase & prevents buybacks
This was a tough one to rate. The hero isn't the greatest right now, which can in part be attributed to the fact that there are so many counters to it these days. The damage increase gained by Aghs isn't great either; it scales as if it were just a level 4 skill. So why is this upgrade good? Simple. The fact that you prevent buybacks is probably the most ridiculous thing in Dota 2. No matter how far down you are, you can potentially win with 1 good pick off (or two with refresher). This Aghanim's upgrade is a win-condition in itself, which you can't really say for many others on this list.

Tier 2: Gaben's Blessing (God Tier)

3
Night Stalker
Darkness
Unobstructed vision at night
Remember the IseeDeadPeople cheat command in Warcraft 3? That's basically this, but in an 1800 area around you. Overall, vision wins games. Couple this with a gem and it's pretty easy to gain map control. Also consider the fact that Nightstalker can manipulate the Day/Night cycle to benefit himself, which makes this ability even stronger (especially when compared to KOTL Aghs). In short, the vision this item provides is game-breaking.
2
Nyx Assassin
New Skill
Gives burrow skill. Max HP and mana per second regen, reduces incoming damage, longer impale cast range, lower impale cooldown, increase mana burn cast range, spiked carapace becomes AoE
This upgrade is pretty god-like. It adds more utilty to Nyx than any other item could provide. The funny thing is that burrowing in itself would be an amazing upgrade alone. Despite the one negative of being immobile, you are provided the following pros: constant invisibility, 40% damage reduction, and 1.5% Max HP & Mana Regen. As if that weren't enough, it also upgrades your other abilities: 1) Impale range increased by 450 & cooldown reduced by 6; 2) Mana Burn cast range increased by 300; 3) Spiked Carapace becomes an AoE stun. Plus you get to sexually identify as a Lurker. Pretty much no negatives that I can see.

Tier 1: Icefrog's Concoction (Class of its Own)

1
Alchemist
Other
Give Aghs to teammates
Generally there is a lot of room for debate among this list. This however, is the exception. Giving Aghanim's Scepter's to your teammates is by far the most powerful ability in the game. It is, as they say, game-breaking. Not only is this amazing on paper, but it's equally amazing in practice. The main reason for this is the fact that Alchemist is able to farm a Scepter with relative ease thanks to Greevil's Greed. Take into account that this not only does not take up an item slot, but also gives full stats to the recipient. This is unequivocally the strongest Aghs upgrade in the game.

Bonus Aghs Idea: Dragon Knight gains Elder Dragon form permanently.