Soul Trap is a skill located in the Soul Magic (which can be found in the World skill tree). Soul Trap is a base skill, and can be morphed into Soul Spitting Trap
or Consuming Trap
Soul Trap 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, Spell Erosion, Thaumaturge. Also the following red champion point trees protect against this skill: Elemental Defender, Thick Skinned.