Item: the Unabridged Dictionary of Hell: While equipped, the player can speak Abyssal and gains advantage on any speech checks made against demonic entities. However, it is rather heavy, and makes the player look like a total nerd, so while it is in the player’s inventory, they must take a -1 to both dexterity and charisma rolls.

(Twist to be decided by DM before use: it was published by demons and is actually completely and purposely incorrect and the demons go along with it because they think it’s funny; roll d20 with each usage, rolling a 1 has the demon being spoken to reveal the ruse)