Rot Lurker

Deathtouch, Trample
At the beginning of each end step, put X +1/+1 counters on each creature you control where X is the number of sources that caused you to lose life that turn. (If you lose life from the same source multiple times in one turn, it is still one source.)
"Pyrexians bite the hand that feeds them. I don't see the problem when I do it to you."
-Fido, Phyrexian Necromancer