Stacking AC through the roof

[BloodSnake'sCha]

I think it's because armor +1/+2/+3 and adamantine armor are listed as separate magic items. Some people feels like this implies they can't be combined. However, under armor +1/+2/+3, it does say any armor. This could mean any non-magical armor, or it could mean any armor, including magical armors.

Now, there are some magic weapons that already add a bonus to attack and damage rolls, making them essentially +1/+2/+3 weapons without them being listed as such. I do think it's a bit silly to try and make them a weapon +3 on top of that, potentially adding a total of 6 to attack and damage rolls. So that could be used as an argument against applying the +X bonus to magical weapons and armor. However, I'd more likely just treat that weapon as if it already had the matching +X bonus. For example, a Staff of Power is actually a Staff of Power +2. You might be able to get a +3 variant, giving a +1 over the standard staff, but you'd never be able to stack a +3 bonus on top of the existing one for a total of +5.

All that said, mizzium armor (GGtR) is an improvement over adamantine armor, so if mizzium armor +3 exists, it's the best no-attunement armor.

With this I fully agree.


Anyway, to the OP.
Just let him have his fun, he can even become the group meme.
Just make sure to target his saves her and there when it is appropriate (like when fighting an evoker that blast the party with evocation).

If a player invest so much in something it is good to make sure they can get the fruit of their investment.

[Snowbluff]

No matter how high you stack AC the opponent will always have a 5% chance to hit you and will always be able to attack you through alternate means, ie save or suck attacks. In order to truly tank up you need to layer your defenses, e.g. high ac plus vision superiority plus high movement plus disguise.

If you are building a character to go beyond ac 30 and you aspire to be a tank then you are doing it wrong.

This is why the Cloak of Displacement is such a strong defensive item. Stronger than armor +3.

This is why my build went with Foresight. It's like a Cloak of Displacement except it works on every attack and vision, as well as helping protect your saves.