The hydra description says, "To prevent a severed head from growing back into two heads, at least 5 points of fire or acid damage must be dealt to the stump (a touch attack to hit) before the new heads appear" (Monster Manual 155–6). The pyrohydra description adds, "Fire attacks cannot prevent a pyrohydra’s stump from growing new heads…, but 5 points of cold damage does" (157)

The creature I'm customizing for a challenging upcoming encounter is a half-white dragon 5-headed pyrohydra. Although consumed with self-loathing, the hydra is immune to fire damage from the subtype fire and immune to cold damage from the template half-white dragon.

A close reading seems to indicate that this creature's stumps can still be prevented from growing heads if a stump—rather than the creature proper—is dealt 5 or more points of cold damage. That is, damage to the stump seems to be tracked separately from damage to the hydra's heads or body.

Is it accurate to rule that this creature's stumps can still be cauterized by cold damage? Or am I reading this description too deeply, and this half-white dragon pyrohydra's stumps are just as resilient to cold damage as the rest of it?


3 Answers 3


the SRD monster description says "Fire attacks cannot prevent a pyrohydra’s stump from growing new heads (since a pyrohydra has immunity to fire), but 5 points of cold damage does." By extension, creature immunity to damage type means that stumps cannot be prevented from growing via that damage type. The pyrohydra's stump immunity to fire is a natural result of the pyrohydra's overall immunity to fire, and thus one might expect a similar result from immunity to cold.

Worth noting, this means that the only way to keep stumps from regrowing is acid damage. I wouldn't throw this monster at a party unless I knew they had a fair amount of access to acid damage (or such was provided on site).

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    \$\begingroup\$ You needn't worry about the party. They'll learn quickly enough to fight the body instead of trying to lop off heads. I mean, that's an absurdly dangerous proposition anyway. (Seriously, who takes the Improved Sunder feat?) \$\endgroup\$ May 1, 2018 at 18:22
  • \$\begingroup\$ I suppose you could slip them a vorpal weapon just before the battle for grins and giggles, but mostly head-sundering is about soaking the one opportunity attack per sunder attempt. Combat reflexes lets the hydra get an opportunity attack per head per round, but it doesn't let them make more than one per opportunity. Still, if the party has enough damage pressure to blow through Fast Healing 15, then that is another way around the problem. \$\endgroup\$
    – Ben Barden
    May 1, 2018 at 19:30

Well since you are homebrewing the mixed breed. it is up to you which immunities/resistances/vulnerabilities you keep. If you keep immunities from both dragon and hydra, the dragons difficulty rating is going to increase substantially.

That said if you keep cold immune, the stumps would also be immune. The stump damage is is a focused attack for the purpose of cauterizing, thus is declared as such; as apposed to general damage for the purpose of killing.

A viable alternative, is to reduce the immunities to resistances due to not being pure blood of either type or allow magical fire/cold to damage the dragon.

Note: Acid still cauterizes the stumps.

  • \$\begingroup\$ Is adding a template to a monster really homebrewing? I feel like here I'm just mixing a cocktail. \$\endgroup\$ May 1, 2018 at 18:08
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    \$\begingroup\$ a hydra is a separate dragon type.. if a white hydra is not specifically listed then technically it is a homebrew, even if using a standard template. Usung the template does solve many balancing issues though. \$\endgroup\$
    – ravery
    May 1, 2018 at 18:11
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    \$\begingroup\$ That sounds like a conversation for another time. (Although I'm compelled to point out that the hydra is a magical beast; a dragon would be deeply offended were it lumped in with typical hydras!) \$\endgroup\$ May 1, 2018 at 18:18

No, since it is immune to any damage caused by a source with a fire descriptor therefore the 5 damage threshold would never be achieved.

If this Hydra was a Laernean Hydra (Savage Species under Multiheaded template) then the only way to kill it would be to kill all the heads before they rose up again since the body would be invulnerable to damage and the severed heads would grow back in a few rounds.


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