Mordekaiser, Iron Revenant

Swampwalk, Trample
Other creatures you control get +1/+1 and "Whenever this creature blocks or becomes blocked by a creature, Mordekaiser deals 2 damage to that creature."
{u/b}{u/b}{u/b}{u/b}, {t}: Destroy target creature, then return that creature to the battlefield under your control. Put two -1/-1 counters on that creature. You can only control one creature with -1/-1 counters at a time.