Yorick Rework concept - ghoul master

I've been ruminating on the idea of Yorick as the master of an army of ghouls for awhile, and ultimately came up with this kit concept for him.

Passive - Together in Death: Yorick is constantly accompanied by two Companion Ghouls who will attack the target of his basic attacks. Companion Ghouls' base health, attack damage and resistances scale with Yorick's level, and they gain a portion of his Bonus Attack Damage and Bonus Health. If one of Yorick's ghouls is dead, he will automatically revive it after a delay. If Both ghouls are dead, he'll revive one after a much shorter delay before moving to the longer delay for the second.

Q - Leeching Strike: Yorick's next basic attack deals additional magic damage on hit and heals him for the amount of magic damage done (his ghouls recover half this amount). If the attack targets an enemy champion, Yorick additionally recovers a percentage of his missing health.

W - Grave Rush: Passively, Yorick gains a burst of movement speed whenever his ghouls attack an enemy champion. On activation, Yorick and his ghouls enter a frenzy, granting Yorick and his ghouls bonus attack speed for the duration. Yorick can target an enemy with this ability to make his ghouls pursue and attack that target for the duration of the effect.

E - Dark Bargain: Yorick sacrifices the targeted Companion Ghoul in an explosion that deals magic damage to and slows all enemies in an area around the ghoul's position. For a few seconds afterwards, Yorick's basic attacks deal magic damage in an area of effect around his target.

R - Army of the Dead: Passively, Yorick accumulates Reanimation stacks when killing units (1 for melee/caster minions, 2 for large monsters and siege minions, and 10 for champion kills/assists and Epic monster takedowns). At 10 stacks, Yorick summons a Shambling Ghoul. Shambling Ghouls behave like Companion Ghouls, but will not be revived automatically upon death and cannot be targeted by Dark Bargain. Shambling Ghouls will persist until they or Yorick are killed. Yorick can have up to 1/2/3 (based on ult rank) Shambling Ghouls at a time.

On activation, Yorick temporarily empowers the targeted ghoul, giving it greatly increased attack damage, health and resistances, and causing his other ghouls to gain the benefit of Grave Rush's attack speed while the empowered ghoul remains active. Yorick can use his ultimate key to directly control the empowered ghoul's attacks and movement.