Crystal Shard is a skill located in the Dark Magic (which can be found in the Sorcerer skill tree). Crystal Shards is a base skill, and can be morphed into Crystal Blast or Crystal Fragments.
Crystal Shard 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.