Vaerena, Mistress of Masks

{b}{r}, {t} : Target opponent choose another
non-token creature you control. Exile it. As long
as it is exiled, other creatures you control gain its abilities and +X/+Y, where X and Y are respectively equal to the exiled creature's power
and thoughness.
When Vaerena, Mistress of Masks leave the battlefield, return all cards exiled with her to the battlefield under their owner's control.