The Collector

When The Collector enters the battlefield,
you may exile target historic card from your
graveyard. (Artifacts, legendaries, and Sagas are historic.)
{2}{b}: Regenerate The Collector.
{x}{u}{u}, {t}: Exile target artifact or creature with converted mana cost X or less.
When The Collector leaves the battlefield, return
all cards exiled with it to the battlefield under
their owners' control.