How does jack bristow die in alias?

Answer 1

Sloane becomes immortal in an underground cave where he finds the Ramboldi artifact, and Jack, whom Sloane shot shortly before, comes down to him. He is dying. Sloane offers his help, however Jack refuses it, telling him how he has 'caused (his) daughter so much pain', and triggers an explosion, which causes the cave to collapse on them. Jack obviously dies. Sloane, who is immortal cannot move, so he stays underground forever - alive. Which is exactly what he deserves.

Jack's last words were 'beat death, Arvin, but you couldn't beat me'.