Balfen, Bathed in Blood

Cumulative Upkeep—Pay 2 Life
Whenever you pay life to cast a spell, or you
pay life to activate abilities of cards you control,
or you pay life for the triggered ability of a card
you control, each opponent loses half that much
life, rounded down.
At the beginning of your end step, put a +1/+1 counter on Balfen for each player that lost life
this turn.