Leif

When Leif enters the battlefield, target opponent
reveals their hand. Choose a nonland card from it
and exile it. You may play this card for as long
as it remains exiled, and you may spend mana as
though it were mana of any color to cast that spell.
{2}{u},{t}: Exile Leif, then return it to the
battlefield as a copy of any non-Legendary
creature on the battlefield, except it's a 1/1 Halfling.
"I made no mistakes and did everything right!"