Thorn energy is a form of infernum created by empuses in Uffern in the Castle of Thorns region of the Palaces in the Hells. It is the energy of temptations. A user of this energy is a Dewin Drain.

Velvet Rose, plants growing in Uffern that are pure thorn energy and can be turned into potions, foods, etc.
Ifreann Duil, invoking thorn energy through rituals of sex and cruelty that causes the invoker to be a source of temptation
Driodair, invoking thorn energy through sleeping in actual thorns while whispering the names of demons