When below 35% health all damage taken is reduced by 20% and your Pyroblast spell's cast time is reduced by X secs while the cooldown is increased by Y secs. In addition, melee and ranged attacks made against you have a Z% chance to disarm your attacker's main hand and ranged weapons.
Fiery Payback is a Magetalent in the Fire tree. It reduces the cast time of the Mage's Pyroblast spell but adds a cooldown to it to avoid spamming when the Mage is close to dying.
It also provides the Mage with a defensive chance to remove their attackers' weapons.