Ransomware Broker

{4}{b}, {t}: Exile target nontoken creature an opponent controls and put a ransom counter
on that card. Any time for as long as that
card remains exiled with a ransom counter
on it, its owner may pay half their life,
rounded up. If they do, return that card to
the battlefield under its owner's control. Activate Ransomware Broker's ability only
any time you could cast a sorcery.