Yorick and hybrid pen runes

It should. Penetration works for all damage you do. For example if I were to by magic pen boots on someone after I buy a sunfire cape. The magic pen would also apply to the immolate passive damage.

Ok really just wondering because the mist walkers an Maiden are like separate "entities". It's not really damage Yorick is actively doing himself. You know what I mean? I appreciate the feedback though because I want to use a hybrid pen rune build and am not sure if it is worth it for him. I was actually thinking of getting Liandries for his E (% health damage on top of % health damage?) It sounds good to me but I'm always looking for different ways to play champs....and it doesn't always work out....