AI should count cards in its hand before playing a Shard of Serendipity.
I just saw it doing a first turn Quantum Tower + SoSe. Was great for me btw.
A second point, but it's more general and I'm not sure how to propose it, but the AI likes to feed player's Otyugh. Even if a big Bone Wall is on the field against him. It's my major Arena farming strat right now.