Accruba Dagger (5e Equipment)
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Weapon (dagger), very rare (requires attunement)
You gain a +1 bonus to attack and damage rolls made with this magical weapon.
Accruba Mode. When you attack and hit a creature that is surprised with this dagger, it must make a Constitution saving throw with a DC of 18. On a failed save, the target takes an additional 2d4 piercing damage from your attack.
Fury Mode. As a bonus action, the user can cut themselves dealing 2d4 slashing damage to themselves. The blade then grows twice it's normal size and glow a fiery red and gold until the start of your next turn. While in this state, the weapon deals 2d4 piercing damage and 2d4 additional fire damage.