Immortal beings will automatically heal afflictions over time. They don't need the Chalice
or Gift of Health. However, the Prince of Death isn't actually immortal, as others have noted.
Probably the best way to use the Prince of Death as a supercombatant (SC) is to give him a lot of Death magic (to boost his innate Fear) and Dominion 9 or 10 (for Awe). The combination of high Fear and Awe can be very effective in preventing melee attacks. It's especially good at stopping units with low Morale, like Barbarians.
Even so, you want a little bit of insurance, because the Prince of Death is a bit fragile. So research Construction 2 right away, and then give him some toys. Black Steel Plate is always nice, and it even matches the scary image of the Prince of Death....
