[Divine] Artifact - Traitor's Tongue

This rapier is a literal fragment of Eurys the Silent Faces, stolen by a worthy champion of the God of Shadow and Trickery. Champions who wield this weapon do so on the tides of chaos with no guidance from the deity, gloriously sowing chaos across the Material Plane.

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Traitor's Tongue
Weapon (rapier), artifact (requires attunement)

If you did not trick, steal, or otherwise deceptively obtain this rapier, you must succeed on a DC 15 Charisma saving throw to attune to it. If you fail, you become poisoned for 1d4 hours. While poisoned this way, you are compelled to give away all your belongings, including this blade.

Semi-Sentience. This rapier is forged from a portion of Eurys's tongue. Traitor's Tongue is a semi-sentient chaotic evil weapon with a Wisdom of 13, and a Charisma of 15. It cannot see or communicate, but can empathically sense the intentions and actions of its wielder. Once per day, if its wielder pulls a deadly or incredible trick, the rapier replenishes 2 expended charges (at GM's discretion).

Envoy. The rapier grants the following benefits while you are Eurys's Envoy:  

• This rapier grants a +1 bonus to attack and damage rolls made with it. 
• You gain darkvision out to 60 feet while you hold this rapier, if you don’t already have it. 
• The rapier has 3 charges and regains expended charges at midnight. When you hit a surprised target with this rapier, you can expend charges to deal poison damage to it. You can expend up to a number of charges equal to your proficiency bonus, dealing 2d8 poison damage for each charge expended. 
• A creature other than you that tries to wield this rapier must succeed on a DC 15 Charisma saving throw or take 2d8 poison damage. If a creature that takes this damage was unaware of this property, the rapier regains 1 expended charge. Once the rapier regains a charge this way, it can’t regain another until the next midnight.

Herald. The rapier grants the following additional benefits while you are Eurys's Herald:  

• The rapier's bonus to attack and damage rolls increases to +2. 
• The rapier’s charges increase to 5. 
• While holding the rapier, you have resistance to poison damage.

Champion. The rapier grants the following additional benefits while you are Eurys's Champion:  

• The rapier's bonus to attack and damage rolls increases to +3. 
• The rapier’s charges increase to 7. 
• While holding this rapier, you can see normally in darkness within the range of your darkvision, both mundane or magical. 
• While holding this rapier, you can use a bonus action to teleport from an area of dim light or darkness up to 60 feet to another similar area. You can't use this property again until the next midnight.

Destroying the Rapier. To destroy Traitor's Tongue, it must be brought to the archdemon Omendacios, the Lord of Lies, and used to replace his tongue. If the archdemon speaks an honest truth with this tongue, the rapier disintegrates into golden dust.

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DESIGN COMMENTARY

Eurys is entirely new, and yes that is a sorta tongue muscle stretched into a sword shape! Pretty gruesome.

This weapon is more roleplay involved than the others, granting the wielder extra charges based on their evilness. It's also an ambusher, trading out regular bonus damage for extra massive damage against surprised combatants from 4d8 to 12d8. The later abilities assist this, such as movement through darkness. Unfortunately not useful for fiend fights (poison immunity), so try not to do that.