Roven, the Manipulator

Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature,
put a +1/+1 counter on this creature.)
{t}, Remove one or more +1/+1 counters
from Roven, the Manipulator: Gain control
of target creature with power less than or
equal to the number of +1/+1 counters removed this way.