Limnus the World Warper

Whenever a creature blocks or becomes blocked
by Limnus the World Warper, exile it.
When Limnus the World Warper attacks, you
may pay {x}. If you do, return up to X creatures
exiled with Limnus the World Warper to the battlefield under your control, tapped and attacking, then exile them at the end of combat.
His portals have swallowed entire armies. They will
when he calls.