as a constitution attack action, you begin to charge an attack, this charging lasts until the beginning of the next round and you cannot move during this charge, once this charge is completed, you release a blast of energy that is a 30-foot sphere that emanates from you, everyone within this sphere must make a dexterity save equal to 8+ your constitution modifier, if they fail, they will take half of the damage you've taken over the course of 4 rounds. if you are hit during your charging, the attack will fail.