I got Rustler on Wednesday; I took one look at that and said 'not happening.' I mean, what kind of deck can you make with that, especially one that the AI can play?
Some of the ones I'd skip:
Other: probably everything except SoG/SoD/pillar (you could maybe do mono-other with animate weapons, or use SoR if you had lots of nymphs)
Entropy: Dissipation Shield. This is a good card, but I don't think it would do well in the arena. For one, unless your wisdom were either 0 or max, you'd have some upgraded and some not. For another, I don't think the AI would play it at the right times.
Death: if you had the right cards, you could probably make any death card work okay.
Gravity: Graviton Mercenary, Chimera. The mercenary just sucks, and while the Chimera has its (rather narrow) place, the AI is really bad with it, and you don't really want five copies of it in your deck. (or ten!)
Earth: Plate Armour. It's pretty bad, one of the worst cards in the game. I suppose you could combo it with Otyugh or something, but I'd skip.
Life: Rustler, Emerald Shield. Rustler is a very narrow card, and I doubt you'd get the AI to use it right. I mean, look at Ferox; often he won't convert light to life on its turn, and even worse, Rustler has an extremely high AI priority for things like Epinephrine or Blessing that you would rather have on almost anything else. Emerald Shield is not that great a shield, though it has its place, but again, like Chimera, you do not want five of them in your deck.
Fire: I think any card here would be playable if you had the right cards to support it
Water: Flooding. Probably this is one of the worst cards in the game, and FIVE copies in your deck? Ugh. Give me Rustler any day over this...
Light: Probably any card would work here if you had the cards to support it. I've already skipped Blessing twice since Arena went live, but that's in large part because I have zero upgraded light pillars/pendulums, so any light deck I made would probably be rather bad.
Air: Thunderstorm. This is probably the worst air card, and I don't think I've ever used it, or even seen it used, other than by random AI decks. You might be able to make a case for skipping Fog Shield or Sky Blitz, not because they are bad, but because five copies is bad.
Time: Procrastination Shield. This is probably the worst shield in the game; I'd probably play Tower Shield over this :p The rest you could probably make a deck around if you had to, like scarab or deja vu, but there wouldn't be much room for creativity.
Darkness: Eclipse, Voodoo Doll, Liquid Shadow. Eclipse gets redundant with five copies, and if you had a mix of eclipse/nightfall due to your wisdom level, the AI will play one of each, which is a waste. Liquid Shadow is the crappiest darkness card, and I'd always skip that. Voodoo Doll isn't bad, but I doubt that any of the good decks using it would be playable by the AI.
Aether: Probably any card here could make a deck, given the supporting cards again.
Some of the nymphs might be worth skipping, but it would be so fun to make a deck with five (or six nymphs, given that you would have just won one from the oracle) that I'd have to try it. The first day arena went live, I got red nymph and made a fire stall deck. I even got to use my SoRs for the first time!
