Arcane Armor Training (Mythic)
You’ve adapted your spellcasting to overcome limitations of wearing armor.
Prerequisite: Arcane Armor Training.
Benefit: You don’t have to spend a swift action to gain the reduction to arcane spell failure chance from Arcane Armor Training. Furthermore, if you’re wearing light armor, reduce your arcane spell failure chance by 20%.
Source: Mythic Adventures, p. 55