Magicka Detonation is a skill located in the Assault (which can be found in the Alliance War skill tree). Magicka Detonation is a base skill, and can be morphed into Inevitable Detonation
or Proximity Detonation
Magicka Detonation deals the following types of damage: Magic 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.