Quick update today with just a few fixes:
1) Titan Arbiter no longer prevents creatures from gaining abilities while it is a corpse.
2) An exploit that would allow cards from opposite Kingdoms to be used in decks (i.e. Elemental cards in a Mystical hero deck) has been fixed. Decks can no longer be saved with illegal cards in them and both the Arena and Guild Wars will now reject such decks, even if they meet all other deck building requirements.
3) We've also added some new code to allow for some new creature abilities in future releases (this has no impact in the current game).