Trait: Unbreakable - Your creatures’ class-specific Shield artifacts prevent 100% of that class’ base damage and heal them for 30% Health when they take damage from that class.
Even without a combo, this trait is obscenely powerful.
Add in a spell like “condemning light” that converts all enemies to the same class and appropriate shields. Congratulations, you have a team that is immune to attack and spell damage.
In general, damage immunity of any sort is easily exploitable so I’d suggest a rework on this trait.