Help with multiple protection spell

[Gabmilot]

I'm DMing a game and the mage is starting to use multiple protection spells on himself and I was wondering which spells stack and which don't.
The mage is level 13 and he's only wearing a normal robe and has a DEX of 16(+3).
He's also wearing a protection ring +2 and bracers of armor +2

Spells:
Dragon skin +5 to AC
Shield +4 to AC
Mage Armor +4 to AC

If everything stack, then he would be at an AC of 30 which is ridiculous for a 13th level mage.
So what would be his real AC?

[flappeercraft]

They all stack. Also AC of 30 is not even remotely close to high for a 13th level character regardless of class. Just as a comparison to what is high, I have a 5th ECL Tiefling which is a LA +1 race that has 43 AC when buffed. 8 levels lower and 13 AC more. Also when taking into account protective effects, all AC bonuses stack when they are different kinds of bonuses. Untyped bonuses and Dodge bonuses actually are the exception as they stack with each other but only if they come from different sources. So Haste and Dodge feat would stack and give a +2 dodge bonus while Haste spell twice would only give +1. Mage armor and Greater Mage Armor don't stack as it gives an armor bonus meaning that only a +6 bonus since it's the higher from both.

[finaldooms]

Mage armor counts as an armor bonus ( just like regular armor) right? If so..then i dont think the bracers of armor +2 stack ..mage armor would override since itz +4 ..but i might be wrong and reading the bonuses incorrectly

[Thurbane]

Just for reference, Racial bonuses may or may not stack, depending on what you consider the primary source (not that I'm aware of Racial bonuses to AC, but anyway...).

PHB (p.171) says they do.

RC does not repeat this information.

[flappeercraft]

Mage armor counts as an armor bonus ( just like regular armor) right? If so..then i dont think the bracers of armor +2 stack ..mage armor would override since itz +4 ..but i might be wrong and reading the bonuses incorrectly

You're right, I sorta skimmed this post and only saw the spells and the robe. Didn't see the bracers of armor so yeah those wouldn't stack.

[Gabmilot]

I did some research:
AC = 10 + Armor + Shield + DEX + Size mod + Others

Others are:
- Enhancement Bonus
- Deflection Bonus
- Natural Armor
- Dodge Bonus

In this case, Enhancement, Size mod and Dodge would be zero.
- DEX is +3
- Armor would be +4 with the mage armor spell (Like finaldooms said it would override the bracers)
- Shield would be +4 with the Shield spell
- Natural Armor would be +5 thanks to Dragon Skin.
- Deflection Bonus would be +2 with the ring since it's considered deflection bonus.

AC = 10 + 4 + 4 + 3 + 2 + 5 = 28

So the only thing that changed were the bracers of armor which were overrode by mage armor.

[John Longarrow]

I did some research:
AC = 10 + Armor + Shield + DEX + Size mod + Others

Others are:
- Enhancement Bonus
- Deflection Bonus
- Natural Armor
- Dodge Bonus

In this case, Enhancement, Size mod and Dodge would be zero.
- DEX is +3
- Armor would be +4 with the mage armor spell (Like finaldooms said it would override the bracers)
- Shield would be +4 with the Shield spell
- Natural Armor would be +5 thanks to Dragon Skin.
- Deflection Bonus would be +2 with the ring since it's considered deflection bonus.

AC = 10 + 4 + 4 + 3 + 2 + 5 = 28

So the only thing that changed were the bracers of armor which were overrode by mage armor.

Correct. Also take a look at the AC and bonus to hit on a lot of CR 13 monsters...

Glabrezu is +20 to hit with an AC of 27
Iron golem is +23 to hit with an AC of 30
Ice Devil is +20 to hit with an AC of 32
Death Slaad is +20 to hit with an AC of 28

His AC is pretty low if the bad guys get close to him, plus ALL of those have nasty surprises that make then less than easy to deal with in a fight. With only a 28 your wizard would be better off trying to get alternate ways to avoid getting hit, like mirror image and displacement.

[tyckspoon]

Mage armor counts as an armor bonus ( just like regular armor) right? If so..then i dont think the bracers of armor +2 stack ..mage armor would override since itz +4 ..but i might be wrong and reading the bonuses incorrectly

That's correct. Bracers of Armor are an Armor bonus, Shield is a Shield bonus, Dragon Skin is (IIRC) basically a version of Barkskin, so that's Natural Armor, and Mage Armor is another Armor bonus. Same bonus types generally don't stack, so you take the higher available one. The character's AC would be 28 with all those effects running (note that Shield is only a min/level duration, which generally only covers one or two fights when you account for travel time/stopping to search the room/cleaning up after a battle. If he wants Shield up for everything, he's either making very effective use of scouting to know when to pre-cast it or he's taking a precious action in every fight that could have been used for a much more immediately impactful spell.) And, as mentioned, that's not all that high - the kinds of monsters that care about attacking AC can generally hit that with at least 50% reliability starting from CR 10.

[Thurbane]

This thread may also have some ideas (focused on items rather than spells, however): [3.5] "Unusual" AC Boost Items (http://www.giantitp.com/forums/showthread.php?512608)

There are also the following bonus types to AC:


Competence
Insight
Luck

..and of course, "untyped".

[Khedrac]

I did some research:
AC = 10 + Armor + Shield + DEX + Size mod + Others

Others are:
- Enhancement Bonus
- Deflection Bonus
- Natural Armor
- Dodge Bonus

In this case, Enhancement, Size mod and Dodge would be zero.
- DEX is +3
- Armor would be +4 with the mage armor spell (Like finaldooms said it would override the bracers)
- Shield would be +4 with the Shield spell
- Natural Armor would be +5 thanks to Dragon Skin.
- Deflection Bonus would be +2 with the ring since it's considered deflection bonus.

AC = 10 + 4 + 4 + 3 + 2 + 5 = 28

So the only thing that changed were the bracers of armor which were overrode by mage armor.
Common mistake, and everything else is right.

It is nearly impossible to get an enhancement bonus to armor class (I think there may be one or two very very obscure sources out there, having sacred and profane bonuses at the same time is way more common).
What enhancement bonuses will be (except for the couple where the author got the rules wrong and broke them) is an enhancement bonus to the item providing one of the other bonuses, usually to armor giving a larger armor bonus or a shield giving a larger shield bonus.

The case where this is important is:
+1 leather armor mighty fortification - 3 armor bonus (2 base + 1 enhancement)
greater mage armor - 6 armor bonus
result = 6 armor bonus to AC (the greater of 3 and 6) for a total of 16 assuming no other modifiers.
Obviously the armor is worn for the fortification effect, the mage armor is providing the AC.

Now, consider what happens when a magic vestment is cast on the leather armour, assume 20th level for +5 enhancement bonus.
+5 leather armor mighty fortification - 7 armor bonus (2 base + Max[1 permanent, 5 temporary] enhancement)
greater mage armor - 6 armor bonus
result = 7 armor bonus to AC (the greater of 6 and 7) for a total of 17 assuming no other modifiers.

If the enhancement bonus was added to the character's armor class directly they would have AC 21.

[KillianHawkeye]

Common mistake, and everything else is right.

It is nearly impossible to get an enhancement bonus to armor class (I think there may be one or two very very obscure sources out there, having sacred and profane bonuses at the same time is way more common).
What enhancement bonuses will be (except for the couple where the author got the rules wrong and broke them) is an enhancement bonus to the item providing one of the other bonuses, usually to armor giving a larger armor bonus or a shield giving a larger shield bonus.

The case where this is important is:
+1 leather armor mighty fortification - 3 armor bonus (2 base + 1 enhancement)
greater mage armor - 6 armor bonus
result = 6 armor bonus to AC (the greater of 3 and 6) for a total of 16 assuming no other modifiers.
Obviously the armor is worn for the fortification effect, the mage armor is providing the AC.

Now, consider what happens when a magic vestment is cast on the leather armour, assume 20th level for +5 enhancement bonus.
+5 leather armor mighty fortification - 7 armor bonus (2 base + Max[1 permanent, 5 temporary] enhancement)
greater mage armor - 6 armor bonus
result = 7 armor bonus to AC (the greater of 6 and 7) for a total of 17 assuming no other modifiers.

If the enhancement bonus was added to the character's armor class directly they would have AC 21.

That's right.

Another important point is that if you applied enhancement bonuses to your AC directly, the enhancement bonus from your magic armor wouldn't stack with the enhancement bonus from your magic shield, which would be utter nonsense.