Karel, Trombone Boss

+1: Add one mana of any color to your mana pool. This mana does not empty from your mana pool until the end of your next turn.
-4: Create a token that's a copy of target non-token creature. The token gains haste. Exile it at the end of turn.
-7: Until end of turn, you may cast spells from your hand without paying their mana costs.