Targets can be debuffed to negative resistance values with a hard cap of -100%. E.g. at -50% resistance the damage will be 1.5x; at -100% the damage will be 2x, this means that with a spellpower of 234 or higher the full hard cap is achieved using just this power, eliminating the need to use Affliction Hex in a boss scenario. (easily possible in Awakening).
Stacks with Affliction Hex.
Currently active spells which cause damage over a period of time such as Walking Bomb or Crushing Prison are not enhanced. The Hex needs to be cast before.