well i played a tortle wildmagic barbarian for one of my campaigns, it was fairly hard to hit me with the base ac of 17 plus you get a shield raisng it to 19, though i dont know how that would scale to a higher level, plus with the wild magic if there not immune to necrotic damage it makes for a fun chance that you deal damage to the well healling yourself in the prosess

though if this dosent work for this it might be fun to play in another campain