Biomancer

While Biomancer is on the battlefield, whenever a creature dies create a 1/2 Organic Entity creature token with Defender and “Sacrifice this creature:
Draw a card.”
{g}{w}{t}: Put a +0/+1 counter on target creature for every attacking creature the opponent controls until the end of combat.
As long as you control a creature with a counter on it, Biomancer has Lifelink.