Mage Armor does not Stack. Nor is it a concentration spell. Can only be removed with Dispel magic and longresting. Them doing it 15 times does nothing.
Shadowheart should not be in Melee. shes a trickery domain cleric. Clerics are spellcasters. Shadowheart can only use a dagger well( Simple weapons proficiency + her dex bonus).Unless at lvl 4 you took a feat to give her prof in a finesse weapon, she isn't going to hit anything, nor should she be. She should only be casting, and long resting when depleted.
When it leaves you with only rare hits and she is healing up the damage you can do every other turn on top of adding mage armor, it is a big thing.
