Yorick minions?

Just a quick question: Do yoricks' minions take reduced damage from aoe spells? I had a game as gragas where my autos insta kill his little guys but the barrel and body slam take maybe 1/3 of their total damage. I had another game as mundo and the cleaver kills his minions in one hit too but his w drains the health bar similar to what was going on with gragas. I didn't see anything about it after a quick search so was hoping for some info if anyone has some!

Thanks!

-normals game scrub