Martin, Obverse Prodigy

Magecraft — Whenever you cast or copy an
instant or sorcery spell, you may {t} and choose
one:
• Replace all instances of "+" with "-" and vice
versa untill end of turn.
• If a player would draw card, that player instead
mills a card and vice versa untill end of turn.
• If a player would gain life, they instead lose that
much life and vice versa untill end of turn.