From The Heroes of Might and Magic III wiki

See also Elixir of Life (Campaign).

This is a combination artifact.

Combination artifacts were introduced in the expansion Shadow of Death,
and are only available when it is installed.

This artifact needs the Ring of Vitality, the Ring of Life and the Vial of Lifeblood.

You cannot purchase combination artifacts in Artifact Merchants. Cost is derived from sell price.

Basic Cost: 100.000 gold

While it provides a 25% bonus in Health to all living (not including undead or non-living units) creatures, the regeneration ability only adds in the base number of hitpoints that a troll has (40), and does NOT necessarily maximize the hitpoints of the actual creatures affected.

Note that the bonuses for the original artifacts still count, but the combo bonus (25%) is calculated BEFORE the original bonuses, so for a Master Gremlin, they only get +1 for the combo, which gives them 5 HPs, THEN the bonuses for the originals kick in (+4 more, for a total of 9 HP).