For AST, why not both card systems?...

[Seraphor]

What about this:

All cards have their current effects, but are 4/8% instead of 3/6%, and no longer give seals.

Minor Arcana transforms the card into a random card, either Lord, Lady or Page.
Each Minor Arcanum gives a different Seal, and acts as either a Heal, a Regen, or a Shield.
So let’s say:
Lord = Shield + Solar Seal
Lady = Heal + Celestial Seal
Page = Regen + Lunar Seal

Or, can keep the current Minor Arcana system of specific cards giving either Lord or Lady, have them be a Shield and a Regen, but then gives a random Seal when used.

Divination is boosted to giving a damage buff of 4/6/8% to the whole party.

The increased buffs are due to you actively sacrificing a card to get a Seal, so you’re basically choosing between regular single target buffs OR an AoE buff.
Which also makes each buff on its own feel more impactful.