Fossilize is a skill located in the Earthen Heart (which can be found in the Dragonknight skill tree). Fossilize is a morph of
Petrify.
Fossilize 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.
ESO Skillbook