This my theory for the ending of the last Harry Potter.
Harry finds all the Horcruxes and destroys them except the Slytherin Locket which Voldemort has. Now Harry and Voldemort are dueling and Voldemort is shooting curse at Harry but Harry blocks them. Voldemort then hits Harry with the Sectumsempra Curse and Buckbeak comes and knocks Voldemort to the ground and starts biting him. Voldemort then kills him. Hagrid comes in furious and loses control and punches Voldemort. Voldemort drops the Horcrux. Hermione heals Harry from the curse and Harry shoots the Horcrux with the Reducto Spell and Vordemort shoots the Avada Kedavra Curse and hits Harry’s scar and backfires. Voldemort then gets killed. Snape then shoots the Avada Kedavra Curse at Harry but bounces of the walls and hits Snape. Malfoy and the other Death Eaters defeated flee.
That's my theory.