Using this skill on an enemy makes them take more damage from all of your damaging skills while it’s in effect. You’ll also be healed a little if you slay a monster before the kiss fades. Since this takes three rounds to use, it isn’t usually worth using on small monsters.
This skill is the primary way for Kharim to advance their “charm” reputation. I’m unaware if this skill offers any meaningful reputation gains to the other chaos guilds, though I have heard it does not.
The in game help reads:
Skill duration: 3. Type of skill : battle skill. Affecting stats: Int/Wis. It uses 10 endurance points. This Lord of Chaos skill allows you to blow a pre-emptive kiss of death to your foe. It is considered to be rude, yet extremely threatening when done right. Killing the foe you've marked is said to help in the search for your chaotic self.