Dragon Encounters

Combat encounter (difficulty 16)

As per the rules, the adult dragon has the ability to make the water surge out and pull them into the water, knocking them prone. I’ve already mentioned in my post on the young black dragon that it seems unlikely that someone knocked prone inside a swamp should be able to regain their footing (non-magically.) If we do that, this lair action should almost automatically win the encounter for it. In addition, they can also do it by beating their wings for two legendary actions. How to deal with it?

You could cheat, and rule that the ground by the dragon’s lair is firmer, giving them a solid footing. The other thing you might do is have them hold themselves up by ropes, giving them a way to prevent being pulled down, at the cost of limiting their mobility. Since players are unlikely to set up the ropes (or better yet chains, as the black dragon will destroy ropes too easily) you might consider using the idea where the dragon demands a virgin sacrifice annually.

The chains will already be there, fixed to the rock, as that is where the sacrifice is chained. The players have the time to rescue the sacrifice before the dragon arrives, and that way there are chains ready and waiting for them to grab onto when they need them. The catch, of course, is that it means they’ll have to stay near the chains, and be ready to grab onto any falling companions as needed.

(If you want to make the danger of falling stronger, you can add biting fish [swarms of quippers statblock], giant leeches or oozes to the swamp water. I don’t think their necessary, but you can decide for yourself.)

Combat encounter (difficulty 15)

A strategy the black dragon might use would be to dam a portion of the swamp. When it sees an invasive force (in the form of a high-level adventurer party, say) it will punch a hole in the dam, causing the water to slowly rise around them. They possibly won’t realize it until it’s already gotten somewhat high and cut off their escape route, and possibly their route to each other. (As an aside, if you add some areas of swamp reeds, or other vegetation, line of site and where they stand will suddenly matter.)

If you’re running the battle in theater of mind, running this will be easy. When you describe where they can stand, you’ll change the details to reflect the current reality. They probably won’t realize that you’re changing it on them for a while, they’ll just assume they remembered wrong. If they’re standing in an area where the water is rising, you’ll have to mention it, but they’ll assume it’s just there, and they might assume that it’s their footing that is somehow sinking.

If you’re using a battlemap, this will be a lot harder. You’ll obviously make notes for yourself before the battle as to how the water will affect the map every round. When they try to enter an area where the water level makes it currently impassible, you’ll have to tell them that something changed. It means that they’ll figure it out a lot faster, but it will still take them a round or two, and even after they figure it out they’ll still have to deal with it.

Combat encounter (difficulty 15)

The third strategy I want to suggest is that the swamp dragon have its treasure, or a part of it, displayed on a large rock/platform in the middle of the swamp. Unknown to the players, the foundation on which it stands is unstable, so that the dragon can let them reach it and then pull it out under them, plunging them into the swamp waters.

(Its treasure will also fall, but that isn’t so hard to fish out. Also, the Monster Manual informs us that black dragons often keep their treasure buried in the muds of the swamp in the first place.

Even more than with the young black dragon, it will have the sandbars near its lair trimmed to form neat lines, to maximize its breath weapon. (With its abilities to swim and fly, this doesn’t inconvenience it at all.)

With Minions: Each dragon has a different way to use minions. The black dragon’s style is to use large amounts of weak forces, and to send them to swarm the PCs. It doesn’t care about the lives of its minions (even by the standards of most evil creatures) and will gladly dispatch them to distract/occupy the PCs, allowing it to use its full force against a single PC, and hopefully finish that one off before the other can come to his/her aid.

It will choose the weakest PC to finish off, both because that one will fall fastest and to puff up its own ego and dishearten its enemies, but if that PC is protected or hard to reach just have it choose the weakest PC that it can easily reach. (The definition of weakest is the one that it can finish off the easiest/fastest.)