Mothrider Cavalry does not function properly. It does not process that it can be cast for 2 mana when alone in hand. Sometimes you can hardcast it regardless, but other times it doesn't allow you to cast it at all. My most recent game was with 2 of these in my hand and 4 mana. The game made me cast the first one for 4 mana, even though it should have been available at 2 mana.