Corruption Heart

At the beginning of your upkeep, put a spore
counter on Corruption Heart.
At the beginning of your end step, deal X damage
to target player, put X +1/+1 counters on
Corruption Heart, and gain X life, where X is the number of spore counters on Corruption Heart.
"The source of the corruption is Spore, the Fifth
evolution of Elementals."
-Antagonist