Hydra (http://www.d20srd.org/srd/monsters/hydra.htm) text includes "...can breathe jets of fire 10 feet high, 10 feet wide, and 20 feet long. All heads breathe once every 1d4 rounds. Each jet deals 3d6 points of fire damage per head."

This ability is not listed as "SU", "SP" or under special attacks, so I was wondering, does each head breathe together in a single area (i.e. 5 headed hydra breathing for 15d6 once every d4 rounds, 1 save) or does each head breathe independently (like attacks; i.e. same hydra breathing 5 times 3d6 each, 5 saves)?

15d6 seems a LOT of damage for CR6 which could be mitigated by being nice and breathing at different targets (for example) so I wanted to be sure which way it worked (as written). Thoughts appreciated.

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    \$\begingroup\$ Second paragraph is garbled: "does each head breathe independently... or does each head breathe independently" \$\endgroup\$ – Dave Sherohman Mar 14 '15 at 11:39
  • \$\begingroup\$ @DaveSherohman I agree and edited; I hope that is more clear. \$\endgroup\$ – joedragons Mar 16 '15 at 17:01

The Hydra breaths once, for 15d6 damage.

All heads breathe once every 1d4 rounds. Each jet deals 3d6 points of fire damage per head.

The first sentence is a bit ambiguous, but the second one is clear. When it says that "each jet" deals damage "per head" that implies that there is a single thing (a jet of flame) made up of many components (several heads working in concert).

This would not be true if each head breathed independently.

"All heads breathe..." is also sort of ungrammatical if the heads are intended to breathe individually. In that case it should be "Each head breathes..."

Add to this the slightly greater amount of book-keeping with doing the heads individually (So, three heads targeted you, but you made two saves, so you take 6d6 halved plus 3d6 not halved...).

As to the amount of damage, remember that the PCs can help themselves out by winning initiative and dropping a few of the heads before the hydra's turn (though doing so is difficult).


Every head of the Hydra breathes once, for 15d6 damage each. However, you should probably run this as if
The Hydra breaths once, for 15d6 damage

These reddish hydras can breathe jets of fire 10 feet high, 10 feet wide, and 20 feet long. All heads breathe once every 1d4 rounds. Each jet deals 3d6 points of fire damage per head.

The first sentence just tells us the dimensions of each jet, which are similar to but distinct from a "line".

The second sentence tells us that all of the heads breathe once every 1d4 rounds. A strict reading thus requires all of the heads to breathe simultaneously, as a round-triggered event.

The third sentence tells us that every jet the hydra produces deals 3d6 points of damage per head the hydra possesses. It does not indicate that any heads but the one producing the jet are used in the production of the jet, just that the damage scales with the number of heads.

This is a lot of damage for many-headed hydras. A twelve headed cryohydra, for example, focusing all of its wrath on a single adventuring party of targets fitting in a 10X10X20 foot line would deal 432d6 cold damage to each of them. This is enough to guarantee a one-shot kill on an equivalently sized pyrohydra. It is also the largest source of cold damage available in the rules, without epic spells (and it's better than most of those, too). Given that this creature is supposed to be CR 13, this is probably not how the hydra is supposed to work.

When I play in or GM high-op games, this high damage output tends to be used, and pyro/cryo hydras are combat monsters of the highest caliber (indeed, half-black dragon half-white dragon 12-headed pyrohydras and their icy half-red dragon half-green dragon counterparts show up much more often than one would expect, given their odd genealogies).

When I GM mid-to-low-op games I explain to my players that the 'per head' phrase at the end of the sentence is a typo resulting from redundancy, and that actually each jet just does 3d6 damage, with all of the heads breathing once every 1d4 rounds. This results in the 15d6 damage total I suggest you use. Remember not to forget the multiple saves, which mitigate the damage output into roughly the expected range for the hydra's CR (it's still above average power at nearly every level!).


I homerule'd it, as 5 independent attackers (who don't get to move independently). Each head can target, and each one fires a blast every 1d4 rounds determined individually per head (so there's not always 3 safe rounds to dash in and do some damage). If you've got a bunch of PCs, all attacking, most of the time a single PC will not receive all 15d6 (or, more often, 30d6 after PCs have attempted to sunder heads and failed to hit with acid or cold to seal) at once.

For targeting for each head, I usually I pick: last person to damage that head, the nearest PC (starts to add up, but I also divide heads as: front, left, right - in this case; 1,2,2), or a still moving PC.

This allows me to more accurately keep track of which heads have been severed, and if they've either duplicated or gotten sealed.

Heads whip around, so there's no problem in attacking from an "off" side, if you've eliminated several heads and are attacking from one direction.

I use 1d4s and quarters behind the screen. I rotate all dies; counting down until their next attack (then roll them again and put them back in place). A d4 goes on a tails-up quarter when it's been severed, but not sealed. And the die is put away when the neck is sealed. Once vulnerable neck time has run out, quarter underneath die is flipped to heads-up; and now does two attacks: duplicated heads on a single neck attack together; but attack rolls are resolved separately.


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