Droma, Spirit-Crafter

Costs {2} less to cast for each creature you have
killed or exiled so far this game.
Heartwood—{b}{b}{g}{t}: Steal half of target
player's life total, rounded down. That player
gains control of Droma at the end of this turn.
{u}{g}: Counter target spell and draw 3.
The soul of my body is ancient, the trees are
my song.