Do Yorick's Ghouls (and other Spawnable entities) trigger Ravenous Hunter?
Solution 1:
Ravenous Hunter is a Drain Effect, so its apply to all damage sources.
Liandry's Torment has 2 passives: Madness stacks w/ any damage you deal; Torment is applied by any Ability Damage, so if your ability deal damage to a unity torment will proc.
Yorick's ghouls do apply spell damage, so yes it works.