Arcane Spell Failure Chance

Armor interferes with the gestures that a spellcaster must make to cast any spell that has a somatic component. Spellcasters face the possibility of arcane spell failure if they’re wearing armor. Spell-like abilities, supernatural abilities, and spells without a somatic component are not subject to arcane spell failure chance.

Casting an Arcane Spell in Armor: A character who casts an arcane spell while wearing armor must usually make an arcane spell failure check. The number in the Arcane Spell Failure Chance column on Table: Armor and Shields is the percentage chance that the spell fails and is ruined. If the spell lacks a somatic component, however, it can be cast with no chance of arcane spell failure.

Shields: If a character is wearing armor and using a shield, add the two numbers together to get a single arcane spell failure chance.

Armor Proficiencies

Any class that provides both armor proficiency and mana points allows the spellcaster some freedom from arcane spell failure chance. While casting spells learned using mana from that class, the spellcaster ignores arcane spell failure chance from armor that class granted proficiency with. A character that has taken multiple classes with differing armor proficiencies must note which class granted the mana used to learn all spells, as they may suffer arcane spell failure chance differently with different spells.

For instance, a character who had gained 50 White mana points worth of spells from Paladin and 100 Red mana points worth of spells from Sorcerer (and possessed no other mana) would be able to cast any of their White spells while using any armor or shield without fear of arcane spell failure chance. However, all of their Red spells would suffer full arcane spell failure chance as sorcerer grants no armor proficiencies. If that character then gained 50 Green mana points worth of spells from Ranger, they could cast all of their Green spells in medium or lighter armor (or while wielding any shield other than tower shields) without worrying about arcane spell failure chance.

A character who has taken the armor or shield proficiency feat(s) may cast in any armor their feats grant them proficiency in without fear of arcane spell failure.

Arcane Spell Failure Chance

Skies of Glass Planeswalker