Deathfire Touch Keystone Hidden buff to Galio?

Against any champ who takes that mastery, he will get tremendous healing via his Bulwark?

At least one champ per game should have this mastery, more if there are multiple apcs or even AD casters who take the mastery as well.

i've only played one game with Galio since patch but I did fairly well at times I felt I shouldn't, perhaps this explains it.