Flail of Tiamat
Weapon (flail), legendary (requires attunement)
- Damage: 1d8 bludgeoning
- Weight: 2.0 lbs.
This magic flail is made in the image of Tiamat, with five jagged heads shaped like the heads of five different chromatic dragons. You gain a +3 bonus to attack and damage rolls made with this flail. When you hit with an attack roll using it, the target takes an extra dice:5d4|noform|noparens|avg (5d4) damage of your choice of one of the following damage types: acid, cold, fire, lightning, or poison.
While holding the flail, you can use an action and speak a command word to cause the heads to breathe multicolored flames in a 90-foot cone. Each creature in that area must make a DC 18 Dexterity saving throw. On a failed save, it takes dice:14d6|noform|noparens|avg (14d6) damage of one of the following damage types (your choice): acid, cold, fire, lightning, or poison. On a successful save, it takes half as much damage. Once this action is used, it can’t be used again until the next dawn.
Source: Fizban’s Treasury of Dragons p. 23