Does mage armour stack with unarmoured defence?

Does Mage Armour Stack with Unarmoured Defence?

In the world of Dungeons & Dragons, armour and defence can make all the difference in combat. Two popular defensive mechanisms are Mage Armour and Unarmoured Defence, each with its own set of rules and benefits. The question on everyone’s mind is: can they be used together?

Direct Answer

In simple terms, the answer is no. Mage Armour and Unarmoured Defence are mutually exclusive, and they cannot be used together to calculate your Armour Class (AC).

The Logic Behind it

Both Mage Armour and Unarmoured Defence are used to provide a bonus to your Armour Class, but they achieve this in different ways.

• Mage Armour: This spell gives you a bonus to your AC when you wear it, using the formula: Your AC = 10 + Your Dexterity modifier + Your Mage Armour bonus.
• Unarmoured Defence: This is a class feature that allows you to calculate your AC using your Dexterity modifier, Wisdom modifier, and Unarmoured Defence bonus. The formula is: Your AC = 10 + Your Dexterity modifier + Your Wisdom modifier + Your Unarmoured Defence bonus.

As you can see, both mechanics calculate your AC differently. If you use Mage Armour, you’re essentially saying you’re wearing armour and adding a bonus to your AC. If you use Unarmoured Defence, you’re saying you’re not wearing armour and adding a bonus to your AC in a different way. Trying to combine the two would create a contradictory calculation.

The Rules That Back it Up

In the official D&D rules, there are several quotes and examples that support the idea that Mage Armour and Unarmoured Defence are exclusive.

• "When you cast Mage Armour, you gain a +2 bonus to your AC while you wear the armour." (Source: PHB, p. 154)
• "If you’re wearing armor, you can’t use Unarmoured Defence to calculate your AC." (Source: Xanathar’s Guide to Everything, p. 130)
• "If you’re using a spell or ability to modify your AC, it supersedes any unarmoured AC you would otherwise have." (Source: SRD, p. 125)

These quotes and examples show that the game designers have specifically designed Mage Armour and Unarmoured Defence to work independently of each other, and that combining the two would create an ambiguous calculation.

Exceptions and Grey Areas

While Mage Armour and Unarmoured Defence are mutually exclusive, there are some exceptions and grey areas to consider:

• Natural Armour: As a creature with natural armour, you can still use Unarmoured Defence to calculate your AC, as you’re not "wearing" armour in the classical sense.
• Magic Items: Some magic items, like a cloak of protection, may give you a bonus to your AC that interacts with both Mage Armour and Unarmoured Defence. However, these items are explicitly written to work with either mechanism, not both.

In conclusion, Mage Armour and Unarmoured Defence are two separate defensive mechanisms that cannot be used together to calculate your Armour Class. While there may be some exceptions and grey areas, the official rules are clear: you can only choose one or the other.