Black Heart (5e Equipment)
From D&D Wiki
Weapon (Dagger), Rare (requires attunement)
A great weapon for stealth and straight out stopping opponents in their tracks.
This weapon allows you to cast Darkness nonmagically as an action, regaining use at dawn. You are not affected by this, and thus may see through it as normal. If another creature casts Darkness, or other magical darkness is applied in this area, the spell affects you as normal.
First strike. If you are in the globe of darkness created by this weapon and you have advantage on the melee attack roll, this weapon's base damage is 4d4.