This spell functions like sword of deception and sword of light, except that you cause a black blade of negative energy to appear and attack opponents at a distance, as directed by you. Instead of dealing damage, a sword of darkness bestows one negative level on each successful hit against a living creature, threatens a critical hit on a roll of 19-20, and bestows two negative levels on a critical hit. Negative levels usually have a chance of permanently draining the subject's levels, but the negative energy from sword of darkness don't last long enough to do so. However, if the subject gains at least as many negative levels as it has hit dice, it dies.