Cynern, the Swarm Lord

Swarm 4 (When this creature enters the battlefield,
create token copy's of this creature with haste equal
to the number of opponents times four. Exile them at
the beginning of the next end step.)

Creature spells you cast have Swarm 2.
Whenever a non-token creature leaves the
battlefield, exile Cynern, then return her to
he battlefield under your control.