Negotiator of Sin

Persist, Skulk, Wither
Whenever Negotiator of Sin enters the battlefield
or deals damage to a player, you may exile a card
in your hand. If you do, target opponent reveals
their hand. You choose a card from it that shares
a card type with the exiled card. Exile that card.
Players may play those cards they don't own for
as long as they remain exiled, and may spend
mana as though it were mana of any type to play
those cards.