Mage Armor

Does using a shield add to your AC bonus and/or end the spell early?

So the main difference is just not being able to dismiss the spell at will as an action? Oh and it's available for wizards twice

You have to have Shield Armour Training to gain the benefits from a shield and it does fall under the armour section in the 2024 PHB so I would sadly say that it will end this spell early yes. 

Page 219

“anyone can don armor or hold a shield” (need training)

On same page “wear one suit of armor or wield only One shield at a time”

seems to still work with mage armor (shield) if proficient 

Quote from Menwy >>

Page 219

“anyone can don armor or hold a shield” (need training)

On same page “wear one suit of armor or wield only One shield at a time”

seems to still work with mage armor (shield) if proficient 

 The spell also says that 'The spell ends early if the target dons armor.' and to me the rules are saying that a shield is armor so it would end if you were to don the shield. 

I am not a fan of it and I may allow a shield and mage armor at my table but if you are doing 2024 RAW then no.

You can “don” armor (wear it) or “hold” a shield. You can’t really don a shield. That would be a fashion faux pas.

Last line of the Shield of the Cavalier and other shields.

Shields require the Utilize action to Don or Doff. You gain the Armor Class benefit of a Shield only if you have training with it.

My main question is does this stack with Unarmored Defense features from various classes?

If so, I could see a Barbarian/College of Dance Bard/Monk/Draconic Sorcerer getting a lot of value out of this since the spell's range is touch.

I could see the spell disabling these features since Mage Armor is technically armor, but at the same time, it doesn't fall into a light/medium/heavy category either, which would mean Unarmored Defense bonuses would still apply.

Armor Class in the Rules Glossary: "If a rule gives you another base AC calculation, you choose which calculation to use; you can’t use more than one."

Is the Mage Armor visible?

Can you cast it on yourself?

If another class gives cha or wizdom to ac does it stack with Mage armor?

yes if you are willing, you can touch yourself.

To the people asking if you can use mage armor with a physical shield:

If you have shield training (which you need, to actually get the AC bonus), you will probably have at least light armour training as well. In which case... just use actual armour, so the use of a shield is unequivocally allowed?

If you're absolutely desperate for 13 base specifically, then while you're wearing Studded Leather, grab a Cloak of Protection. As an added treat you get +1 to saves with it as well.

Using a shield adds to your AC because the spell says "the target’s base AC". In the rules glossary, your base AC is equal to 10 + your Dexterity modifier, and a shield just adds a bonus to your AC if your proficient with it.

You don't don a shield.  You hold it.  So it is most definitely allowed RAW.  Wording matters.  

what always pissed me off is that mage armor actually uses dex not int modifier making it kinda meh in my opinion unless u max dex wich u seem a bit forced to do 

You can use this spell to lower enemies AC's, particularly dragons who have a significantly lower DEX score compared to their natural armor, lower their AC by 4 or something for half the day with no concentration or save, and bewilder your DM!

and that is what charisma is for, it is still really useful for this purpose if you only use a little bit of social manipulation. 

Yes, but my main point with the original post was that this spell specifically says "Until the spell ends, the target’s base AC becomes 13 plus its Dexterity modifier.", It sets the AC.

Also those rules you are referring to are specifically in the Multiclassing, class features section and specifically references the Monk's Unarmored defense and the Sorcerer’s Draconic Resilience feature which both say "your base Armor Class equals" compared to this spells "the target’s base AC becomes".

This section also starts out with,

When you gain a new level in a class, you get its features for that level. A few features have additional rules when you’re multiclassing. Check the information about multiclassing included in each of your classes’ descriptions.

Special rules apply to Extra Attack, Spellcasting, and features (such as Unarmored Defense) that give you alternative ways to calculate your Armor Class.

 which means that rule does not apply to this spell.