Joker, Agent of Chaos

Instant spells you control cost {1} less to cast
Anytime and opponent casts a spell that targets you
or permanents you control, create a mayhem creature token.
creatures you control have haste.
Anytime a player is to take damage flip a coin, if heads, that player takes no damage. If tails, that player takes double the damage.
Anytime another player casts an instant spell, you may exile the top card of your library. You may cast that card until end of turn.