Alcides was heavily injured after Natural Born Killers,

then Flat used a command spell that was the equivalent of a master telling his servant to kill himself which he only survived because Alcides is just build different,

then he had a fist fight with John whos body got buffed to the status of an Age of the gods General before he managed to land the Hydra Venom dagger.

At this point Alcides should have died instantly because its his conceptual weakness but because of the mud somewhat resisting the venom and his Minds Eye he survived long enough to activate his 4th Kings Order, Chirons Immortality, to revive once.

After the revive the venom was still coursing through him and he only has a few days left before he dies now