I think the main problem is AI doesn't know when it's better to wait to play a card, or play cards in the wrong order in its turn.
Many examples :
- AI uses purify as soon the card is available, even if the opponent has poison creatures/weapon in play and the poison counter is low (a better script would be if opponent use poison, only use purify if poison counter is say > to 30% of remaining hp)
- AI immolate creatures even when it has no use for the produced quanta, losing the dammage they can make (even worse for immo arena decks AI instantly immolate low attack creatures having an usefull ability, ie chrysaora or vultures if photons aren't available)
- AI immolate/kill creatures in front of opponent's bone wall, when this bone wall can be destroyed by not killing anybody (a better script would be only feed opponent bone wall if you are near death and need to kill those creatures to survive)
- AI play creatures with low hp in front of fire walls/thorn carapace (here it may sometimes be usefull to finish an opponent, but the chances to do so should be reduced in early game)
- AI plays soul catcher or bone wall after killing/immolating creatures in the same turn when they could have been played before
- AI doesn't consider waiting to use shard of readiness, and will waste it on any creature having an ability, even if lots of the needed quanta is available
- AI doesn't consider waiting to use quintessence, and will waste it on any creature if nothing strong/having an usefull ability is on the field (including creatures like scorpions needing buff to do dammage)
- AI waste deflags on pilars when opponent already has lot of pilars and quantum, instead of waiting for a shield/strong permanent to remove (a better script would make the AI only use deflag on pilars if the opponent has less than 4 or 5 of this kind and low quantum)
- AI waste momentum on weak creatures, even just before playing a stronger one (ie cast momentum on a gnome gemfinder just before playing a shrieker)
Edit two more specific problems I just witnessed :
- shadow or death/light half blood kill their own creatures trying to heal them with holy light
- AI prefers to steal an hourglass over a permafrost shield, that despite all its creatures are blocked by the shield (seen trying a minor vampire + adrenaline arena deck) ; in general AI obsession for stealing hourglasses is a big AI weakness when the opponent can be killed in 1-3 turns by stealing its shield (especially when AI doesn't have the time quantum income to use those hourglasses)