Do Yorick's ghouls and the damage they deal count as ability damage, and specifically, would they trigger the rune Ravenous Hunter, and heal me based on the damage they deal? I can not find conclusive evidence.
Ravenous Hunter does not apply on Yorick's Ghouls. The ghouls don't apply spell effects.
They are not an ability, it strictly only applies on Yorick E and the % health damage that his ultimate deals.