What about Polar Warbears?
In terms of Elixir of Life, this is designed for use on a dead hero or at least their corpse so no reason why that couldn't restore them back to their max as written.
Although I have specified that it needs to be used on the corpse of the Dead Hero as it was very open ended as originally written and that combined with my stricter rules below makes its use more limited.
2 What Happens to A Dead Hero?
As a Player, if your Hero dies, you are out of the game for the remainder of the game. You may, however, create a new Hero and play him as a new character in the next Quest. Armour, weapons, and treasures that belonged to you prior to death may be lost in the Dungeon.
Warning! If you die, all items that you are carrying will be dropped on the square where you were killed and will be lost to the denizens of the dungeon and will be removed from the game unless the square on which you died remains within sight of at least one other Hero.
In that instance your possessions remain on the square and can be picked up by any Hero moving onto that square or searching the room containing that square.
Note: When a Hero dies, remove the figure, and replace with a skull tile to mark the square in which they died. If, in the unlikely event of more than one Hero death then use skull tile with the number that matches the starting BP of the Hero that is “8” for the Barbarian, “7” for the Dwarf and so on. Place their character sheet and cards in a central position on the board. At the point when they die and at the start of each of their subsequent turns, check whether it can be seen by at least one other Hero, if not then remove the character sheet and cards from play. Leave the marker in place as this indicates where the Hero was killed.

= white skull, one "hit"

= black skull, one "hit"

= shield, cancels out one "hit"
HQ Major Versions: "Classic Edition" - 1989 First Edition [FE] and 1990 Second Edition [SE]), "Remake" - 1990 Remake [NA], 2021 Reprint [21]
HQ Golden Rules Rule Fixes based on the Classic edition.
HQ Common Notification System to identify squares on the board