Helmoth Dagger

=== Helmoth's Dagger ===
Weapon (dagger), unique (requires attunement, see below) 
This weapon functions as a +3 dagger, even when wielded by a creature that is not attuned to it. 
Unlocked. While you are attuned to the weapon and you hit a humanoid creature with an attack made with advantage using this weapon, you roll all additional damage granted by class features or spell effects twice and use the higher of the two rolls.