Storm God's Blessing
“This was it; his day had finally come. The storm cleric dropped his mace as his enemies surrounded him. He pulled out his reliquary, a stone he had found in the temple’s basement, and began to pray to the storm lord. He felt the blade go through his heart, followed by a shock. A white light blinded him, and as his vision slowly crept back, he saw the charred remains of his enemies sprawled around him. His hair stood on end, as static flickered through the air. The stone crumbled in his hand as thunder rumbled in the distance.”
While this stone is in your possession, when you are reduced to 0 hit points, regardless of whether or not you are killed outright, your body is struck by lightning, and you regain consciousness with 3d10 hit points. Each hostile creature within 5 feet of you must make a Dexterity saving throw. A creature takes 3d10 lightning damage on a failed save, or half as much on a successful one. Once this item is used, it is destroyed.