Enter the Vortex

When Enter the Vortex enters the battlefield,
exile all creatures your opponents control.
{1}{b/r}{u/b}{u/r} Target one creature exiled with Enter
the Vortex, you may cast that creature as if it was
in your hand paying mana of any color to cast it.
If Enter the Vortex leaves the battlefield, return
all remaining creatures exiled with it to the battlefield under their owners' control