Certain Golems, and undoubtedly other creatures that are less easy to get on a party's side, are affected by certain magical effects differently than most other creatures. Mainly, the Iron Golem and Ice Golem aren't damaged by fire or cold damage respectively. Instead, it grants them temporary hitpoints. The exact wording is as follows, and is the same for either golem aside from the name of the creature and type of damage.

A magical attack that deals fire/cold damage heals an iron/ice golem of 1 point of damage for each 3 points of damage such an attack would otherwise deal. If the amount of healing would cause the golem to exceed its full normal hit points, it gains any excess as temporary hit points.

Now, I can not find a maximum of temporary hit points that these creatures can reach. Nor can I find out whether or not these temporary hit points decay over a certain amount of time.

Do these hit points last indefinitely until removed through damage? If so, is the potential of hit points either of these golems could have actually infinite?

  • \$\begingroup\$ @Fering 3e doesn't have a general rule that says temporary HP don't stack. \$\endgroup\$
    – Carcer
    Commented Apr 7, 2019 at 13:33

1 Answer 1


If the DM rules that the source of the temporary hit points is the iron golem's extraordinary ability magic immunity, a creature like an an iron golem (Monster Manual 136-7) can't gain nigh-infinite temporary hit points in the way the question describes That ability, in part, says

A magical attack that deals fire damage breaks any slow effect on the golem and heals 1 point of damage for each 3 points of damage the attack would otherwise deal. If the amount of healing would cause the golem to exceed its full normal hit points, it gains any excess as temporary hit points. For example, an iron golem hit by a fireball gains back 6 hit points if the damage total is 18 points. (137)

And the Rules Compendium on Temporary Hit Points, in part, says

Temporary hit points gained from multiple applications of the same effect don’t stack. Instead, the highest number of temporary hit points gained from that effect apply.

This ruling is similar to a ruling made by the FAQ in the exchange beginning Do temporary hit points from two applications of the same effect stack? (113). (Note that some folks have issues with the FAQ (see here) and with the RC (see here).)

Thus were an iron golem to have gained temporary hp due to its magic immunity from one fireball then gained temporary hp from another fireball, only the temporary hp from the fireball that provided the most temporary hp would apply.

However, the Player's Handbook on Temporary Hit Points (146) doesn't mention these restrictions on temporary hp. While it can be argued that temporary hp are a bonus of sorts and should not, if from the same source—like a golem's magic immunity—, "combine for cumulative effect" as per the PH glossary's definition of stack (313), that's not often an argument that's entertained.

Therefore in a campaign wherein the DM doesn't use the RC or the FAQ, the DM may rule that, for example, the source of the iron golem's temporary hp is, instead, an individual fireball and that each fireball grants the iron golem temporary hp on top of any previous temporary hp and that an iron golem can gain nigh-infinite temporary hp from repeated exposure to magical fire attacks, no matter the kind.

Such a ruling, though, cascades mightily throughout the game, and the PCs may, for example, eventually end up facing a vampire (MM 250-3) that's used its supernatural ability energy drain many times in the hour before encountering the PCs, each new use of its energy drain ability possibly being considered a different source of temporary hp. With this in mind, this DM and this player recommends hewing with the FAQ and the RC on this issue.

  • \$\begingroup\$ In case of vampire I think there is a clause in a general description of energy drain that limits those temp hit points to last only 1 hour. \$\endgroup\$ Commented Apr 7, 2019 at 18:32
  • \$\begingroup\$ @annoyingimp And who knows how many times the vampire's used that ability in the hour before the PCs arrive? (I'll fix it anyway, though.) \$\endgroup\$ Commented Apr 7, 2019 at 19:09

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