Aghanim by Unfawkable

Arcane Siphon:
-The charges work similar to Bristlebacks Quill spray charges, a single buff with a number, but each buff reduces independently after its 8 seconds have passed.
-Won't gain charges from illusions or hero clones.

Arcane Lance:
-The spell has no projectile speed, it impacts the target are immediately upon cast (Imagine a purple arcane laser covering the ground).
-The Status resistance debuffs stack.
-Will grant multiple Arcane Siphon charges if multiple heroes are hit.

Arcane Twister:
-It basically summons a tornado (like the Wildwing ripper) that can move and explodes after 3 seconds.
-On level 1 with 200 movespeed, any hero without boots should be able to outrun the explosion radius if they start running immediately.
-Each tick of damage grants 1 Arcane Siphon charge, granting a maximum of 6 total before the explosion.
-The Twister has to be always manually controlled, it can't be set to follow an enemy unit.

Arcane Surge:
-The vector targeting is just like Pango's Swashbuckle. You hold the left click on the ground (The point where the rift will open), and then point the direction of the surge towards where it will push and damage units.
-The wall slam damage is a second damage instance and will give Aghanim an extra Arcane Siphon charge.
-Like Arcane Lance, Arcane Surge has no projectile speed and spreads over the target area instantly.
-The push speed is the same as force staff of 1200.

Arcane Avatar:
-Every time you deal magical damage with a spell (Except with the Arcane Twister DPS, only the explosion counts), the duration gets refreshed and all other spells except the spell you used to deal damage are refreshed. For instance, you use Twister, then if you miss Surge, but hit with Lance, you can cast twister and Surge again.
-Proper usage of this ultimate can make you formidable since it can theoretically go on indefinitely or until you run out of mana, but you are still equally frail.
-The moving while casting part means that your hero won't stop for the 0.5 seconds cast time but will instead keep moving in the direction given before the spell cast (Unless issued stop command).
-Arcane Surge pierces spell immunity while under Arcane avatar, which means that spell immune units will be pushed and slowed from the level 15 talent through spell immunity, but not dealt any damage since it's magical.

Aghanim is envisioned to be a mid core or a position 4. On mid his role is not much different from Zeus (And like him heavily countered by BKB and Pipe), all of his spells offer damage that scales as the fighting goes on provided he can keep his distance and some utility. He is incredibly frail with 15 starting STR and barely 1 armor, but compensates for his threatening lane presence with high move speed, short CD and mana cost Arcane Lance, while also being able to use Twister and Surge defensively. He is a high risk high reward hero, and can keep being relevant in late game thanks to his passive and his ultimate which can wreak havoc in a team fight.

As a position 4 he is similar to Dark willow, he is formidable in lane with proper setup for Twister, or he can roam and surprise people with Arcane Surge from afar.

Example skill builds:

Mid: W-Q-W-E-W-R-W-E-E-E-T-R-Q-Q-T-Q-R

Even with the short CD on Arcane Lance, the damage is low to max it and shines later in the game when you can stack up your passive, and the status resistance reduction is constant. While it can be used for easier last hitting, it would be usually better to take and max Twister as it can zone the opponent a lot more easily and potentially do a lot of damage if they don't run on time. Alternatively Surge can be maxed making its uptime a lot shorter and used to setup Twister instead. Both Twister and Surge should be maxed before Lance however, as both have scaling cooldowns while Lance only scales damage. 2 early levels in lance could sometimes be justified if you can land it consistently.

Position 4: W-E-Q-E-E-W-E-W-W-T-R-R-Q-Q-T-Q

As a position 4, twister is still a go to spell, however you can also take Surge as the disposition can sometimes be as powerful as the stun. The Surge is maxed for its much needed uptime and cheaper mana cost, with ultimate being skipped until level 11 since you will likely not have the mana to support it.


Talents:

Level 10: A choice between more status resistance reduction and the most powerful level 10 movespeed talent. Usually the status talent should be taken over movespeed when you have a disable/debuff heavy team, but you can still take it for yourself as well to prolong your Twister stuns.

level 15: Level 15 is the utility level. You can either prolong your only real disable to hefty 2.5 seconds, or take another disable and a way to handle spell immune units better by slowing them (Under the effect of your ultimate only).

Level 20: Arcane Lance damage should mostly be taken on the mid build as it helps you scale immensely, while the Twister range talent ensures you can alternate long range twisters and long range lances while under Arcane Avatar as a position 4.

Level 25: The final powerspike into late game should be taken according to how the team fight have been going thus far. If there were short violent team fights with long time in between, take the duration talent, otherwise, take the cooldown talent. The duration talent helps wait out BKB durations and still have a chance to use your ultimate's potential.

Core:

Veil of Discord - Completely self explanatory. Literally all of his spells do magic damage, and all the item stats are welcome, especially armor and regen.

Aether Lens - All 3 of his basic abilities benefit from Aether Lens, but Arcane Twister most of all increasing the cast range by 50%, which can alleviate your pick of the level 20 range talent in favor of damage. Would also make real long range Arcane Lance snipes possible during ultimate.

Atos - Offers great tanky stats and gives you excellent setup to reliably hit your spells during Arcane Avatar. Core on pos 4, but should be taken instead of Aether as it falls of later. As a mid position you would pick 2 out of these 3 items as core.


Situational:

Eul's Scepter - The stats are amazing, Int, huge mana regen for his huge INT gain, the movespeed to his already high movespeed, and can be used defensively or as setup for twister/Surge.

Dagger/Force Staff - If you are overflowing with farm, keep the momentum with dagger and chase down the opponents, especially if you already have Euls for cheeky escapes. Force against the likes of Naix, Riki, etc.

Ghost scepter - Everyone knows when you build ghost scepter.


Extension:

Bloodstone - Hitting all your spells during Arcane Avatar, but running out of mana fast? Look no further. Also adds some tankiness.

Aeon Disk / BKB - In late game you will likely be burst down as soon as you pop your ultimate, or even before that. On of these should prevent that.

Scythe of Vyse - Even more setup and a powerful disable for late game.

Aghanim's scepter - Your opponents have no spell immunity or BKB carriers? They have your prodigal son Rubick and a Pipe? You want to be thematic? Go for it.


Do not get:

Orchid - While stats are okay, the attack speed is wasted with Aghanim's super low Agy and no way to actually keep the target in place after silence without hitting twister. Atos is a cheaper and better alternative.

Octarine - Sure, you'll have more uptime on your ultimate, but considering what the ultimate does unless you have a lot of active items it's mostly a waste and you'll have better options for the cash.

Kaya - Really? You want 2 stacks of your passive? Sure, I guess. The manacost reduction is nice, but bloodstone helps there a lot more.