Propagator Drone

Devoid
Creature tokens you control have evolve.
(They have "Whenever a creature you control
enters, if it has greater power or toughness than
this token, put a +1/+1 counter on this token."
They see this creature enter.)

{3}{g}: Create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this token: Add {c}."