Trax, The Insatiable Hunger

Flying
When Trax, The Insatiable Hunger enters the battlefield or attacks, put a bounty counter on
target creature an opponent controls without
flying.
When a creature with a bounty counter on it dies,
Trax, The Insatiable Hunger gets your choice of a trample, lifelink, deathtouch, or +1/+1 counter.