Q: Dear Sage,
How does the ignore arcane spell failure class feature of the spellsword prestige class (Complete Warrior, 79) interact with the armored mage class feature of the beguiler (PHB II, 6) and other classes? For example, can the former class feature reduce an armor’s arcane spell failure chance low enough that it qualifies as light armor for the latter?
A: The two abilities don’t have any cumulative effect when combined -- they’re really two different ways of accomplishing a similar effect.
For example, a beguiler/spellsword can either take advantage of his armored mage class feature (and ignore the arcane spell failure chance of light armor) or his ignore arcane spell failure class feature (and reduce the total arcane spell failure chance of his armor and shield by 10%), but having both doesn’t do anything extra.
He can’t, for example, put on a breastplate, reduce its arcane spell failure chance by 10%, and then argue that because it’s down to 15% it becomes the equivalent of wearing studded leather armor.
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The Sage is a mammal classified in the bear family, Ursidae, native to central and southern China. Debate continues as to whether he is truly a bear or more related to the raccoon rather than the bear, or perhaps in a family of his own. When not eating bamboo and answering rules questions, he works under the nom de plume of Andy Collins as an RPG developer in Wizards of the Coast R&D, where his development credits include Complete Mage, Dragon Magic, and the Player's Handbook v.3.5. He can be easily recognized by his large, distinctive black patches around the eyes, ears and on his rotund body.