Version 0.9.4 introduces two new enemy types that only appear when their cards are in your hand. When their cards are drawn in your hand, the next wave will include them as additional enemies. If you have enough coins they can be avoided by drawing a new hand.
Cherbi
The Cherbi is a light enemy, and increases its moving speed 5x when it is two steps away from the knight.
Ilkhan
The Ilkhan is a medium speed enemy, and has a tremendous amount of hp.