The Beguiling Blade

Those who swear loyalty to Slaanesh, chaos god of excess, forswear all forms of restraint. To the foolish, this looks like the promise of freedom, but in truth such pleasures enslave mortal minds to the pursuit of more. Those that follow Slaanesh most closely become his-her beguiling blades, mortals who take on the power and speed of his-her beloved daemonette children.

Dark Prince's Charm

At 3rd level, the Dark Prince has imbued you with his-her wit and charm, giving you power over other creatures. Once per long rest, you may use an action to attempt to charm a creature, forcing them to make a charisma saving throw or be enthralled by you. This charm does not end if the target takes damage, only after a duration equal to a roll of your sneak attack die or if another creature cures them of the charm through magic or a persuasion check. Creatures charmed in this way will perform any task that you ask of them as long as these tasks do not directly place them in harm's way.

Creatures that you have charmed are treated as your allies and count as “enemies of your enemy” for sneak attacks even if they are allies of your target.

Pleasure from Pain

At 9th level Slaanesh imbues you with his-her heightened senses and boundless hunger for depravity, granting you a number of wicked abilities. You have three uses of this ability per long rest, which you can use to Learn Dark Pleasures or Inflict Cruel Pain.

• Learn Dark Pleasures: As a bonus action you may make a charisma check to attempt to assess a creature through the Dark Prince’s eyes, with a DC equal to Deception. On a success Slaaneshi him-herself whispers secrets about that creature into your mind. You learn that creature’s armor class, current hitpoints, gain advantage on charisma checks against them, and Slaanesh will tell you one of the creature’s darkest secrets if they have any.
• Inflict Cruel Pain: You may use your reaction to reveal one of the creature’s secrets to it, distracting them. You may use your reaction to force a creature that has failed to save against this feature, to gain advantage on attack rolls against them by distracting them with their darkest secret. You may also use this feature against a creature that you have learned a dark secret about through other means, and the DM will determine if the secret is substantial enough for the target to be sufficiently distracted by it.

Depths of Depravity

At 13th level the Dark Prince imbues you with a lust for pain, giving you a magical power to enhance the suffering of those you strike. When you land a sneak attack against a creature, you may attempt to empower the strike with Slaaneshi corruption. If the target is below half of its original hitpoints, the damage of that attack is doubled. Once you use this feature, you cannot use it again for 6 days, even if it fails.

Demon of Excess

At 17th level your patron Slaanesh bestows upon you the highest honor any mortal champion of chaos can receive, the honor of being a demon prince. For now your power is still limited, only allowing you to assume your true demonic incarnation for a short time, but that power will grow. As a bonus action you may transform into the form of a Slaaneshi Daemon prince for 20 minutes, gaining the following benefits.

• Your creature type becomes fiend and you may grow to be one size larger if you choose (you decide when first using this ability).
• You gain angelic or bat-like wings that grant you a flying speed of 40ft. Additionally you gain either a set of sharpened claws, a second set of arms with large pincers, or a tail ending in a live snake. These appendages are all treated as finesse weapons that you are proficient in, dealing 1d6 slashing damage per attack and an additional 1d4 psychic damage is your psychotropic venom ravages your foe's mind.
• You gain an extra use of your Pleasure from Pain and Depths of Depravity features per day. Additionally, Pleasure from Pain now regains its uses every short rest and Depths of Depravity regains its uses every dawn.
• You become proficient in persuasion and deception if you weren’t already.

At 20th level, you may ascend into a Deamon Prince permanently, removing the time restriction from this feature but preventing you from transforming back.