Answer:
Leo dies in Blood of Olympus, yet comes back to life
Step-by-step explanation:
Leo had the physician's cure given to him by the god of healing, Asclepius.
He used the help of Hazel to work with the mist and create a fake vial of the physician's cure and handed it over to Piper because according to the prophecy, either Jason or Leo (or Percy, as he could bring storm too) were going to die in the end. "To storm or fire the world must fall."
They wanted Piper to use the philosopher's cure to bring back the one who dies using physician’s cure. But Leo had other plans.
He modified Festus, the figurehead (and dragon) such that it could inject the cure into him when he dies. So, as he burst into flames, killing Gaia, he became alive as Festus injected him with the cure.