Question about the Mage slayer feats.

[Korivan]

Does the one that ignores AC bonuses work on all spells? Including haste and foresight? Also, does it bypass enchantment bonuses with armor? Buddy and me have different interpretations on this.

[Divide by Zero]

Yes, it works on all spells. No, it doesn't work on magic armor, because that's not a spell.

[Uncle Pine]

Yes, Pierce Magical Protection automatically dispels all the spells and spell effects that grant an AC bonus, even if the AC bonus isn't the spell's main effect. Yes, this includes Haste and Foresight. The feat doesn't negate AC bonuses from a magic armor or a magic shield, but works wonderfully against Mage Armor and Shield.

[Troacctid]

It should bypass enhancement bonuses granted by magic vestment though.

[Mr Adventurer]

Yeah - it also dispels Alter Self and Polymorph while in a form with more natural armour than usual. Arguably it also dispels these spells when in a form that grants you more Dexterity than normal, and if so, also dispels Cat's Grace etc.