This is a card that requires removal from the game or a banning on all formats. Rework can be easy – Battlecry: Your next creature costs 1. When paired with Kun, once played there is no way to win. You get hit with 20+ damage, 0 mana moonfires… This way you get the double critter out BUT do not get to OTK chain it.
Much balance is needed! Remove this card, asap. Replace it with a battlecry.