Entropy is a skill located in the Mages Guild (which can be found in the Guild skill tree). Entropy is a base skill, and can be morphed into Degeneration
or Structured Entropy
Entropy 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.