Question about Shield bonus AC stacking

[Valeron]

Does the paladin spell Shield of Warding's shield AC stack with Man-At-Arms shield line of bonus feats?

[DM Narshe]

Shield Block
Type of Feat: Class Ability
Prerequisites: Man-at-Arms 2nd level
Specifics: Your expertise with shields allows you to position it in such a way that a normally dangerous blow is deflected harmlessly. As you gain experience your competence with shield blocking increases and you gain additional shield AC while a shield is equipped. +1 at second level, +2 at 11th level, +3 at 21st level and +4 at 30th Man-at-Arms level. This bonus Shield AC stacks with any permanent enchantment present on your shield.
Use: Automatic

It shouldn't stack.

[Valeron]

The reason I had this question is that the last line of the description on the class page says "This Bonus AC stacks with any permanent AC present on your shield OR other forms of shield AC." Its the last half of that sentence that makes me wonder what they mean. I wouldn't think they would be referring to the "Shield spell" since its not permanent.

[DM Narshe]

Likely referring to the shield itself. +2 for heavy shield, for instance.

Your source is the bgtscc wiki, I assume. Mine is the forums here. They sometimes don't match.

From my understanding of the game mechanics, I -think- that a shield with +2 permanent bonus and +4 bonus from a spell should take that +4 bonus. So it would stack as long as the shield itself gets the bonus when you examine it after casting the spell.

So it probably stacks mechanically, but it's not supposed to based on the feat description.

[mireigi]

The formula for AC gained from a shield should be:
Base AC + Enhancement + Sacred + [Extraordinary|Supernatural]

• Base AC is 1 for Light; 2 for Heavy; and 4 for Tower.
• Enhancement is whichever is higher between a stat on the shield and whatever Enhancement type shield AC buff is active on the character.
• Sacred usually comes from magical effects, such as Shield of Warding, and cannot be found on items.
• Extraordinary and Supernatural are only from class feats such as Shield Block*.

Neither type of AC stack with other sources of the same type.

*: It is possible that Shield Block has been implemented as a Sacred buff to shield AC, in which case it would be the higher of Shield Block and Shield of Warding that gets applied. However, Shield Block is not a magical effect, and should therefore either be Extraordinary or Supernatural.

[AlwaysSummer Day]

It should. My maa/wiz/dd/PM's shield spell stacked with it. Nothing quite like 70 ac . . . .