The Mark of Slaanesh

Slaanesh, youngest of the four major Chaos Gods blesses the flesh of those who worship, with a decorative permanent body alteration in the shape of Slaanesh’s symbol. Slaanesh is a corruption of the Aeldari term Slaaneth (Slaa meaning "ecstasy" or "pleasure" and Neth meaning "lord" or "prince" in the Aeldari Lexicon; hence, the "Prince of Pleasure"), though ironically, the Aeldari refer to this foul entity only as Sai'lanthresh, "She Who Thirsts." 

Every time you level up you gain a permanent +1 to your Charisma ability score as well as a -1 to your Strength ability score (up to a maximum of five times). 

Slaaneshian Charm. Pleasure, Excess, Decadence, Lust, Pride and Self-indulgence. Once per long rest, In a manor you choose you can use an Action and attempt to charm a creature you can see within range. It must make a Charism saving throw, and it does so with advantage if you or your companions are fighting it. If it fails the saving throw, it is charmed by you until the spell ends. The charmed creature is friendly to you. When the spell ends, the creature knows it was charmed by you. to cause the targeted creature to make a Charisma saving Throw. (DC = 10 + CHA mod.) Range/Area (30 ft), Components (V, S), Duration: 1 Hour.