Amon, The Fallen Xel'naga by Maximus Ultima

Amon starts the game with a movement speed 30% lower than usual.
Amon's auto-attacks strike the main target twice and cleave enemies next to the target.

Amon gains a stack of Dark God every time a hero, allied or enemy, is killed within exp range.
Each stack of Dark God increases Amon's move speed by 3% of normal.
Maximum of 20 stacks. Amon's movement speed increases from -30% of normal with 0 stacks to +30% of normal with all 20 stacks.
15 stacks are lost upon death.

Cooldown: 15 sec.
Drains 10% of an enemy hero's maximum health, restoring Amon's health by the same amount of damage done.

Cooldown: 12 sec.
Amon charges into a target, knocking them back and damaging them.

Cooldown: 18 sec.
Amon roars, terrifying any enemy hero or minion within melee range. Affected units are stunned for 1.5 seconds, and deal 50% less damage and are vulnerable for 1.5 seconds after the stun wears off.
Damaging stunned or weakened enemies heals Amon for 50% of the damage dealt.

Cooldown: 65 seconds
Opens a portal into the void that spawns 1 minion every second. The minions will attack the nearest enemy within a certain range of the Rift or itself, and will move toward the nearest lane if there isn't an enemy nearby.
The Rift continues spawning minions until it either closes after 15 seconds or is destroyed.
The Rift has 700 health.

Cooldown: 80 sec.
Creates a surge of Void energy that blasts outward from Amon. The blast causes a semi-randomized amount of damage and negative status effect to each enemy hero that is struck.
The maximum duration for every status effect is 5 seconds. Ignores non-hero units.

Here are the chances for the amount of damage, the type of status effect, and the duration of the status effect. 

Amount of Damage	Status Effects	Duration of Effect
0-100: 40%	Blind: 25%	1 second: 25%
100-200: 30%	Silence: 20%	2 seconds: 30%
200-400: 20%	Root: 20%	3 seconds: 20%
400-600: 10%	Vulnerable: 15%	4 seconds: 15%
	Stun: 15%	5 seconds: 10%
	None: 5%

If this is too complicated, making it completely random works too.

Amon does not have a mount.
Amon can teleport from the Hearth to any intact Fort or Keep, requiring the same channel time as Hearthing. Amon can only teleport to Forts or Keeps from the Hearth.
Amon always teleports behind the target structure.