Multi-headed monster underwater- can it breath with only one head above water?

[ParagonDireRaccoon]

I'm working on an encounter with a five-headed chromatic dragon fighting PCs underwater. It's a large or huge size dragon (young adult or adult) and will trigger a switch that will flood the cavern with water. I'm thinking she can breath by keeping one head above water (providing a big advantage, there will be a pocket of air directly above her). But I wanted to hear others' thoughts on how that would work, and if there's anything I haven't thought of that I should include. I'm thinking only the lightning and cold breath weapons will work underwater, and I'll have the head surface for air the round before breathing the weapon and add a round to the cooldown.

[Bandw2]

depends, i suppose. if there's only one pair of lungs, heck even if there are multiple you could, the others just got to make sure not to breath in while submerged.

[DM_Blake]

Which color is it?

Black and green can breathe underwater anwyay, no need to keep their heads up.

I cannot imagine that a desert-dwelling blue dragon uses a water trap to defend its lair, nor does it seem likely that a red dragon would either.

That leaves white which could be fun - it has a natural swim speed but no water breathing so it might need to stick a head up there, but not every round; it can probably hold its breath(s) for a few rounds at a time.

Your post makes me think that you're considering one head of each color. If so, then I suggest it gains many of the natural abilities of ALL its colors which means a 5-headed chromatic dragon should have water breathing anyway since two of its heads can do that.

For breath weapons, I think fire becomes steam and does the same damage in the same cone. Black and Green dragons specifically say they can use their breath weapons freely underwater so that should not be a problem.

[ParagonDireRaccoon]

Thanks Bandw2 and DM_Blake! It's a dragon with one head of each color. I think I'll set it up so the red, blue, and white heads need to get air every few rounds, and there will be a pocket of air above the dragon. PCs will be able to get use the pocket of air to breath but will risk opp attacks from the dragon.

[DM_Blake]

This is going to be very tough. It has 5 heads, which means 5 AoE breath weapons, and in between, lots of biting and clawing and wing buffets and tail slaps.

The PCs won't be ready for water so might not have water breathing spells and items handy so may expose themselves to much danger trying to get air - they're better off trying for rocket tag and killing the dragon before they swim to the air pocket.

[Queen Moragan]

5 headed white dragon with lair filling ice-cold water defense.

That would be one mean & nasty white dragon!

He could use Vordaki's water trap room from Kingmaker, make the water murky too, and then use electric eels!

[ParagonDireRaccoon]

Thanks DM_Blake and Queen Moragan!

I'm working on a half-reverse dungeon adventure, so the players may face a five-headed dragon in one half of the adventure and play the five-headed dragon facing a group of evil NPCs in the other half. The BBEG is a red dragon guarding an artifact both groups are after. There are two routes, so the players will play PCs taking one route and also play the monsters defending the other route. Most of the encounters will not be identical and will use different but similar monsters. The five-headed (one of each color) dragon will be the same on both routes, but the water option can be used if a group is at full strength at the second-to-last encounter. The set up is the PCs will level up (and do a videogame style level up with full hp and new spells) assuming the beat the BBEG, then fight the evil NPCs withing a few rounds of their victory over the red dragon.

I won't be running this for about a month, but I've run the players controlling the five-headed dragon encounter before. If the body moves each round and each head gets an attack or breath weapon, the dragon basically kills on NPC per round. I have to set up terrain so it's easy to get cover against breath weapons. And both routes will have corpses with dragon-fighting consumables from previous adventuring groups.