Crippling Grasp is a skill located in the Siphoning (which can be found in the Nightblade skill tree). Crippling Grasp is a morph of
Cripple.
Crippling Grasp 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, Thaumaturge. Also the following red champion point trees protect against this skill: Elemental Defender, Iron Clad, Thick Skinned.
ESO Skillbook