Magma Armor is a skill located in the Earthen Heart (which can be found in the Dragonknight skill tree). Magma Armor is an ultimate. Magma Armor is a base skill, and can be morphed into Magma Shell or Corrosive Armor.
Magma Armor deals the following types of damage: Flame Damage. Which means that it gets buffed by the following blue champion point trees: Elemental Expert, Elf Born, Master at Arms, Spell Erosion. Also the following red champion point trees protect against this skill: Elemental Defender, Iron Clad.