Rusty, Giver of Nightmares

Whenever you cast a Rusty spell, gain control of
target non-rusty creature. If opponents do not
control a non-rusty creature, then return target
non-rusty creature from an opponents graveyard
to your battlefield. If opponents do not have a
non-rusty creature in their graveyard, search
target players library for a non-rusty creature,
and put it onto the battlefield under your control.
Then shuffle that players library. You may not
search the same players library more than once a
game