Does Mage Armor have any advantages over Studded Leather +1 or even Studded Leather +2?
From the description of the Mage Armor spell:
You touch a willing creature who isn't wearing armor, and a protective magical 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.
Compared to Studded Leather +1.
Regarding Mage Armor, ...
- You don't need proficiency with any armor (instead of light armor proficiency)
If you wear armor that you lack proficiency with, you have disadvantage on any ability check, saving throw, or attack roll that involves Strength or Dexterity, and you can't cast spells.
Your AC becomes "13 + Dex modifier" (equivalent)
You are not considered wearing armor (better)
- This means you can benefit from traits for which you need to be "unarmored" like a Monks unarmored movement or the Magic Item Bracers of Defense.
- special attacks from some creatures can destroy/weaken your armor
- You need to spend a spell slot, maybe two depending on the length of your adventuring day (worse)
- You only need 1 action to cast Mage Armor vs. 1 minute to don Studded Leather Armor
- You would lose all benefits while in an Anti-Magic-Field while magic Studded Leather armor would still count as a mundane version of it. (Thanks, Yuuki)
- Your defenses could be dispelled with Dispel Magic. This would have no effect on a magic item. (Thanks, Erik)
- You do not have to carry the weight of an Armor (Thanks, Xavon_Wrentaile)
There are a number of benefits to Mage Armor:
- Wizards do not have armor proficiency: Because wizards have no armor proficiency, they suffer major penalties and cannot cast spells while wearing armor (PHB 144). You'll have to expend resources to get a light armor proficiency, which is nontrivial (multiclassing or feats):
If you wear armor that you lack proficiency with, you have disadvantage on any ability check, saving throw, or attack roll that involves Strength or Dexterity, and you can’t cast spells.
- +1 armor is a rare magic item: Because of 5e's bounded accuracy system, +1 armor is actually pretty significant as a magic item. Given that most characters will only ever have a few magic items, a +1 armor will either be very hard to get at lower levels, or represent a significant fraction of a character's magic item wealth. In fact, according to the table on DMG 38, in a standard campaign, characters starting at levels 17-20 only have one rare magic item period. On the other hand, Mage Armor is a level 1 spell, which is far easier to get.
Mage Armor and +1 Studded Leather are largely equivalent.
The only main difference between Mage Armor and +1 Studded Leather is how long it takes to actually equip the armor in question. With light armor, it takes 1 minute to suit up, whereas it takes only 1 action to cast Mage Armor.
The actual AC that the character in question has is similar in both cases; 13+Dex for the Mage Armor, (12+1)+Dex for the +1 Studded Leather. If we add the +2 Studded Leather to the mix, it comes out slightly ahead on AC, at (12+2)+Dex, but still has the drawback of longer equipping time.