Xulamoth's Phalanx

Statistics
Weapon (Dagger), legendary (Requires attunement by a spellcaster)

While this weapon is on your person you always have the following spells known and prepared, according to your caster level.

By keeping one hand on this weapon, you may attempt to afflict a creature with a Hex of Gullibility, as an action. You can attempt to use this ability once per short or long rest.

Hex of Gullibility
Target one humanoid creature within 30 feet. That creature must make a DC 14 Wisdom Saving Throw. On a failed save, the target creature has disadvantage on saving throws to resist being Charmed or Frightened, as well as any Enchantment spells that do not cause damage, such as Suggestion. In addition, when other creatures are attempting to Deceive, Intimidate, or Persuade the afflicted creature, those creatures have advantage on their Charisma (Deception, Intimidation, Persuasion) checks. This effect ends after 8 hours, or until dispelled by a Remove Curse or Dispel Magic spell.

Curse of the Pernicious
When you cast a spell, instead of using a spell slot, you can take Xd8 of unresistable necrotic damage, where X equals the level of the spell. This ability cannot exceed the maximum level of spells you can naturally cast. (For example, if you are a 5th level Wizard, the highest level spell you can cast is 3rd level. Therefore, you may not take 4d8 necrotic damage to cast a spell at 4th level.)