26 May Mage Armor 5e D&D Guide 
A classic for wizards, Mage Armor, offers a bump in armor class for casters who are not proficient in any armor. Generally, casting classes have the fewest hit points, which makes it hard to pass this spell up at early levels.
The rules for Mage Armor can be found in the Players Handbook on page 256.
Mage Armor 5e
Abjuration 1st Level
Casting Time: 1 Action
Components: V, S, M (Apiece of cured leather.)
Duration: 8 Hours
You touch a willing creature who isn’t wearing armor, and a magical protective force surrounds it until the spell ends. The target’s base AC becomes 13 + its Dexterity modifier. The spell ends if the target dons armor or if you dismiss the spell as an action.
The rules for Mage Armor are pretty straightforward. The base armor class of the target increases to 13 and then has the dexterity bonus applied. They also clearly layout the restrictions and ending conditions for the spell.
Is Mage Armor Good?
The benefit of Mage Armor is highly disputed among the community. It comes down to the personal preference of the player. The type of character and the other spells that are available also play a factor in considering if Mage Armor is good.
Mage Armor effectively grants a +3 change to a character’s base armor class. A single cast lasts for 8 hours or the majority of an adventuring day. It is available at 1st level and can be used on other characters. The spell ends if the target puts on armor. Several of these rules present interesting scenarios to evaluate the benefits of the spell.
Scenario 1: +3 to AC
This is a mathematical question that can be evaluated based on the odds of being hit.
- With an AC of 12 (10 base+2 dexterity modifier), there is a 40% chance of the wizard being hit on a flat 1d20 roll.
- With Mage Armor providing an AC of 15 (10 base+2 dexterity modifier+3 Mage Armor), there is a 20% of being hit on a flat 1d20 roll.
- Spell casters, in general, are some of the lowest hit point characters in the game. Being able to reduce the odds of getting hit from just under 1 out of 2 attacks to 1 out of 4 attacks is significant. This is especially true at lower levels when a single hit can drop a caster to 0 hit points.
Scenario 2: Spell Slots
- Mage Armor is a 1st level spell. The argument against it is based on the limited number of spell slots available. Spell slots are limited at lower levels, but that means it is an equal restriction across all spells.
- Shield is one of the other defensive spell options available at 1st Shield grants a +5 to armor class for 1 round and can only be used on the caster. Compared to Mage Armor, Shield will burn through spell slots with significantly less protection provided over time.
Spell casters like wizards and sorcerers are the lowest hit point characters in the game. If the survivability is low for these classes, consider making Mage Armor a cantrip. This gives these classes the opportunity to add to their AC and gain an extra spell slot. The range should be changed to self if used in this manner to help with balancing.
Does Mage Armor Count as Wearing Armor?
Mage Armor does not count as wearing armor for any reason. The purpose for the spell is to provide an extra AC boost to characters who do not wear armor. None of the bonuses, advantages, or features gained by wearing armor (if any) would apply.
Does Mage Armor Stack with Unarmored Defense?
When a character is provided two ways to calculate armor class, they choose one of the methods. Mage Armor calculates AC as 13+dexterity modifier. Unarmored defense calculates AC as 10+dexterity modifier+ constitution or wisdom (barbarian or monk). This means that Mage Armor does not stack with unarmored defense.
For comparison, Bladesong does stack with Mage Armor. Since Bladesong is a bonus to AC and is calculated in the same manner, the two stack. Other spells that grant bonuses to AC without changing the way it is calculated would also stack – Shield of Faith, for example.
Which is Better Mage Armor or Magical Light Armor?
Wizards are not proficient with light armor using standard character creation.The rules for casting spells say that a caster must be proficient with the armor they are wearing to be able to cast spells. This means to be able to use any armor as a wizard, a feat must be taken to gain proficiency in at least light armor.
Mathematically, it might make sense at higher levels to use magical light armor instead of the spell. For example, Studded Leather Armor is the best AC light armor. It provides an AC of 12 +dexterity modifier. Acquiring a suit of +3 Studded Leather Armor would give the wizard an AC of 15 + dexterity modifier (12 studded leather+ 3 magical bonus+ dexterity modifier).
Magical items of this quality are incredibly hard to come by at lower levels and may never be acquired over the course of a campaign. Also, with so many other useful feats available, it seems risky to take for the chance of using it later.
Mage Armor is a classic spell. It has been around through multiple versions of the game because it works. The balancing that has gone into this spell makes it a solid choice for any wizard. With the bonus to AC, it provides, it is also one of the most effective spells that can be cast at 1st level.
The duration makes it reasonable to cast long before entering danger, and the slot lost could be picked up through Arcane Recovery.