The Sword of Surkan

An orb of glowing blue light appears in your hands and lightning roars in the sky. Your hand is hit by a bolt, and a glowing sword of pale blue light appears in your hand. Aggressive creatures in a 30-foot circle around you make a Constitution saving throw, taking 4d10 lightning damage on a failed save, and 2d10 on a successful save. You may use the sword for the next three turns (3D12 + 5 slashing damage), then it disappears in a flash.