Dhauggota in Wake of the Watcher

[Respectable Hobbit]

This encounter seems particularly difficult to run since it's underwater. For the most part, I'm really not sure how targeting and visibility works into and out of the submersible.

First, the text says there's a continual flame lamp inside the Isinglass that must be shuttered if the characters want to see outside, but then there's no light inside. I don't understand why the lamp has to be shuttered to see outside? And if it is shuttered and there's no light, how do they see at all? Are they just relying on Darkvision and spells or what?

Second, how well can Dhauggota see to target characters inside the Isinglass? I'm thinking if it's dark inside the submersible and the devilfish has to attack through a 3-foot wide hole, then he's got a 20% miss chance for concealment and the PCs have a +2 cover bonus to AC. I'm worried the PCs will just hide inside the Isinglass and pelt him with ranged attacks and it'll turn into a very boring encounter. But the same goes for the PCs. How well can they see him, and can they even see 100 feet underwater with no light to begin with? Or am I missing something?

[Victor Zajic]

There is light coming from the Mi-Go dome under the water.

Tonight, when it's dark, go to a window and look out it with the lights on, and the lights off, and tell me which is easier to see out of.

The windows in the sub give line of sight, but not line of effect.
The hole in the bottom on the sub gives both.

Have the summoned sharks ram the sub so it rocks and some water seeps in the hole. If that doesn't get some PCs to exit the sub, have them start to mess around with the air hose. Also, a few lightning bolts through the hole will get their attention very quickly.

Be sure to very carefully research the rules for underwater combat, and explain them to your players ahead of time.

I think Dhauggota has darkvision. If not, there is still the light from the Mi-Go dome. Also, the helm of underwater action they can find negates any sight penalties underwater, if I recall correctly.

[ThreeEyedSloth]

Also, it's very likely that one of your players may use the Helmet of Underwater Action to swim outside the sub, since its awfully cramped in there. If so, then Dhauggota has no problem finding someone to target with spells.

[Maelstrom25]

I just ran this encounter a couple weeks ago and I was expecting some of the same concerns, but my players proved to be very adept at planning for just such a possibility. They know they're going to go to the lake bottom in the submersible, and they know there may be skum down there. If they don't plan for a potential underwater fight, they're not very good adventurers. My party took the time to ask the owner of the apothecary to brew them all potions of touch of the sea which gives them a swim speed and their cleric prepared waterbreathing that morning before setting out. With those two spells, there was little hindrence to them fighting outside the sum, and in fact two of them rode outside the sub as it descended. I think it's meant to be a pretty difficult fight, so I'd enjoy it as a DM, since your monsters have a home turf advantage and are better geared towards fighting in that terrain. The PCs are a high enough level at this point that they should have the resources and abilities to survive it.