See, the way I see AST's current issues is this:
SB AST was good because unique card effects, bad because 4/6 of them were 'not damage' and therefore pointless
SHB/EW AST was/is good because every card is damage, bad because every card is the same effect (damage, more damage if you get the role right)
So why not just... Take the good aspects of both and combine them? That is, 'every card deals damage' and 'every card is unique'? Just have the method by which the damage is dealt per card, be different based on the card used. That way, the 'unique utility' of each card eg Bole's Mit or Ewer's MP regen, those can be 'bonuses on top' that you can choose to prioritize over the damage if you feel it'd be better for the run (eg you need to recover from a death, or the mit going on a squishy for a hard raidwide they keep dying to). So I'd do these effects:
Balance = 10% damage up
Spear = 10% Physical damage up (priority target: Melee)
Spire = 10% Magic damage up (priority target: Caster)
Arrow = 10 stacks of 'your autoattacks are 400% faster', 12 for PhysRanged (priority target: PRanged)
Ewer = 3 stacks on a Healer of 'your spell hits a second time for 100% potency, but cannot crit or DHit' (priority target: Healer)
Bole = 3 stacks of 'counterattack when you are hit, dealing a hit equal to 10% of your Max HP' (priority target: Tank)
If all 6 cards are balanced to have roughly equal damage output, there's no reason to 'fish' for one. Especially if the Seals weren't removed, since they incentivize you to prioritize filling those out and getting all 3 Seal types, rather than playing the same 1 card over and over. By having something like the above, it also means that there's a proper reason to play a card on a Healer or Tank again, something that SHB removed (except for wacky DRK burst trickery)