Originally Posted by Ephemerant
Originally Posted by Aeliasson
The Barbarian feature could use a better description that clarifies that is sets your character's BASE AC to a new value.
I would normally agree with you, but it's not a Barbarian exclusive problem. In 5e, AC calculation is explained and tells you how things interact. You always take the highest value of AC amongst features and spells, certain items and spells can raise AC like normal, some can't, things like that. So honestly, not clearly explaining AC is the real problem.

And really, Unarmored Defense isn't changing your base AC. Base AC has always been 10+DEX modifier. The feature is treated the same as Armor calculation, but doesn't require you to use armor.

That's the problem. D&D is a game that's true to rules as written over feelings and guesswork., Larian overlooked that. Unarmored Defense in 5e rules states that it replaces armor class, not adds to it. BG3 does not. Which means the way both are written, they need to stack. The actual abilities don't stack normally and I said that in my post that it should be updated to reflect that. The way they're written is game is that Base AC for Mage Armor is updated from 10 to 13 if not wearing armor. Unarmored Defense states that if the barbarian is not wearing armor, their AC is Base Armor, plus Dex, Plus Con. By that definition, they should stack and a string fix is easy to do.