Disruptive Dissonance

Enchant player
At the beginning of enchanted player's upkeep,
that player flips a coin. If it comes up heads,
spells they cast with an odd mana value cost {2} more to cast until the player's next turn. If it
comes up tails, spells they cast with an even
mana value cost {2} more to cast until the
player's next turn. (Zero is even.)