About the undead side effect:
Mostly it discards uncommon cards which you really need and it interchanges it with a rare card which is too expensive to play (or you don’t want to play like Battalion of fear) the idea for this side effect is a great one, but it’s more a negative one, than a positive…
About cleansing: If the enemy is an undead player, is it the dead for him! The good undead cards need other undead cards in hand, but you don’t have them anymore! What shall you do now? You also don’t have other cards; you just have got these annoying Purified ashes cards in your hand. If you try to discard them you lose 4 turns, if you try to ignore them, you will lose, and the card militia also doesn’t work well.
That’s just one thing, what’s not okay, but I would need many, many sites to write all the things which are great, you did a very good job Mojko!