Dragon Encounters

Making dnd combat fun, finding monsters that fit together, monster tactics and strategies, and other ways of using the monsters of dungeons and dragons

ANCIENT GREEN DRAGON: Master of the Subtle Trap


Combat rating 24


1 Ancient green dragon (CR 22)

1 Rakshasa (CR 13)


Combat rating 27


1 Ancient green dragon (CR 22)

1 Maralith (CR 16)

3 Yuan-ti abominations (CR 7)

2-3 Giant apes (CR 7)


Combat rating 28


1 Ancient green dragon (CR 22)

3 Erinyes (CR 12)

1 Ice devil (CR 14)


Combat rating 29


1 Ancient green dragon (CR 22)

1 Aboleth (CR 5)

1 Marid (CR 11)

2 Clay golems (CR 8)

2 Grey slaads (CR 9)

1 Death salad (CR 10)

1 Ultroloth (CR 13)

How to Use (difficulty 24)

By the time the dragon is ancient, it will set extremally subtle traps. (The adult might use these also, but the ancient will use them for sure.) These are traps where the trap itself is so well hidden that there is a good chance that its enemies won’t even find it, but the ones that do will be sure of it not being a trap, given how hard they had to dig to find it.

(In D&D, you can increase the odds, letting the players find NPCs with knowledge, and/or provide other knowledge that will lead them into it. Still, you shouldn’t give them more than one or maybe two hints [two only if both are small], and they should conclude that it can’t be a trap. In fact, the dragon should not have been involved in any way that he wouldn’t have been if it had been something real instead of a trap. The dragon was carefully not involved ever since it set it up, a hundred years or more ago.)

A pair of examples follow:

Trap 1: One example would be a rumor of a magical item that can defeat the dragon. The dragon will be known to squash the rumors, but in reality, it will carefully gauge the situation [via secret minions, such as human double agents] and be careful to only squash most of the knowledge.

The item will be hidden in a trap filled dungeon, as nobody would expect such an item to be easy to acquire. In addition, if its enemies are killed trying to obtain the item, that’s a fine result as far as the dragon is concerned.

The area where the dungeon lies has a large number of dangerous monsters in it. The dragon isn’t directly involved in keeping the monsters there, as it would avoid being associated with doing so were the item real, so as not to draw attention to it. It might, however, be slightly less subtle with how it has its minions draw the monsters in. Even so, it will try to keep its minions’ involvement slight, or use minions that aren’t so associated with it.

In short, it will act exactly as though the item wasn’t a trap, except perhaps slightly less subtly.

The item is real. It would be too easy for the adventurers to realize the tap though Identify, or through higher level magic even if it found a way to fool identify. What examining the item won’t reveal, however, is that there is a second item designed to take out the first item and everyone near it. The dragon, of course, has this second item.

Trap 2: Every so often, tribute is brought to a clearing in the forest. Perhaps it’s openly called tribute to the dragon, perhaps it’s officially to an idol in the forest not far from the dragon. What happens to it afterwards is kept secret. All that is known is that at some point, when no one is around, it disappears from the clearing.

What actually happens is that there is a minion or minions assigned to pick it up and bring it to a hidden tunnel very near the dragon’s lair.

The ones picking up the treasure take all precautions to ensure that they won’t be tracked, including stationing scouts to watch as they go past to see if anyone is following, traveling through branches, leaves, or soft dirt to detect invisibility, and either taking a path underground or through a part of the forest thick with low trees so that flying creatures can’t follow. They should use a charm against scrying as well.

For extra credit, you can even add taking a boat, crossing a bridge which they take down after them, and/or passing the treasure to a separate minion as further precautions.

Most of the minions don’t know where the treasure ends up, and the ones who know are fiercely loyal, unlikely to break even under torture. They think that revealing the doorway that they take the treasure to would actually be betraying the dragon.

(You can probably leave it up to the players to figure out how to find out where they’re taking the treasure. Players at these levels are all but invincible, and they’ll probably manage it without too much difficulty.)

The tunnel leads down a passage, perhaps with 1-2 more traps guarding the passage, and is then placed on a dais in a dead-end room. A careful examination of the room will reveal a well-hidden doorway.

Everything until here is intended to be found.

The doorway, contrary to expectations, does not lead to the dragon’s lair. Opening the door triggers the release of a large amount of acid that will wash through the tunnel. Some of it will go into the floor, where it will break ropes that will cause the entrance to seal shut or cave in. It might also trigger the other traps, just to add to the players’ woes.

(As to how the dragon collects the treasure, the dais on which the treasure is placed can be triggered remotely, at which point it sinks into the floor and turns over, depositing the treasure into a small underground room. Once in a hundred or more years, the dragon sends someone invisible in to collect the treasure and bring it back out, before killing that minion in order to keep its secret safe.)

Combat Encounter (difficulty 23)

I already suggested by the adult that the meadow outside be considered part of the lair. For the ancient dragon, I would go a step further and place a lake outside of the cave, and make the entire lake be part of the lair.

(If you’re a strictly by the book DM, you can place the lake inside the cave instead. There are plenty of underground lakes on earth. It’s less scenic, and it will prevent the dragon from flying overhead, but it shouldn’t change the encounter all that much.)

Traveling over the water will probably require a boat, or other water vehicle [I.E. a raft]. While there are spells that will let the PCs swim, fly, or walk on water, they take concentrating, which means the dragon can drop them into the lake halfway across. In addition, it would seem natural for the dragon to have a large number of dangerous fish in its lake. Of the movement abilities, only fly will protect them from these.

(Swarms of quippers, and/or both normal and giant crocodiles seem natural choices. If you’re willing to homebrew, have the lake be swarming with poisonous fish. You can use the swarm of quippers statblock, just raise its damage to 8-9 d4, with 3d4 being piercing damage and the rest poison. [like the regular quipper swarm, this will go down by half when any given swarm is down to half HP.] If we’re homebrewing, an underwater roper would be lethal.)

Among the problems with paddling across a lake is that it is slow. It will give the dragon far too many opportunities to use its breath weapon, or to drop boulders or tree trunks onto the players’ craft, to sink it. In addition, there are at least two other traps that the dragon might employ. (Unfortunately, they’re incompatible. You’ll have to choose one.)

  1. The dragon has its thorn wall, summoned by its lair action, acting as a dam to stop up the river. This is at least part of the reason that it’s a lake in the first place. (The thorn wall lasts until the dragon dies, or uses the lair action again. There is no reason it couldn’t be left up for centuries.) When crossing the lake, it uses its thorn wall against them, thereby creating a current as the lake begins to drain, and pulling the players’ craft downriver.
  2. As the players begin to cross, if not before, the dragon smashes one or more barrels of oil and lets them start to drain into the lake. While the dragon can’t set it on fire, the players can. Fire spells are very common, and if it places its wall of thorns in front of them, it will be even more likely. Oil on water is not highly visible, nor are oil fires easy to put out. Such a fire might do a bit of damage to the dragon, but it will be devastating to the players.

Another nice trick you might have the dragon use is to have its treasure coated with poison, to the extent that it’s deadly to the touch. You could use this in negotiation, with the dragon letting the players know that its treasure is useless to them, so that they’ll be less motivated to fight it.

You could also use this as a trap, with the dragon letting the players capture some of its treasure, knowing that doing so will kill them. While a dragon letting any part of its treasure be taken seems unrealistic, the dragon is doing it with the expectation of taking it back, with interest, off of their dead bodies.

(Even so, the dragon will probably keep the really good parts of its hoard in the back, or behind a false wall. In addition, I would imagine a large number of gold-plated lead and glass gems to be among the hoard, if it’s employing this strategy. As long as the first few layers of treasure are real, the dragon has a good chance of getting away with it.)

A similar trick would be to let the PCs manage to reach the treasure, only for the dragon to escape via back entrance and then loop around to lock them inside the lair and let them starve. Given that this is the dragon’s hoard, they’re unlikely to expect such a reversal. Then dam up the river flowing through the lair (with wall of thorns  lair action, or otherwise,) and let them drown. (It would probably be a good idea to ward against teleportation magic.)



Have the dragon plant a
false magical item that can supposedly defeat the dragon, then quash the rumors
of its existence, but not well. They won’t find out the item is rigged until
they’re facing the dragon.

Hide the existence of a
secret entrance, supposedly leading into the dragon’s lair, but let the players
manage to discover it. In reality, it’s one big trap.

Place a lake swarming with
poisonous fish in the front part of the dragon’s lair. It’s an extremally hard
obstacle to get past, while the dragon is acting to stop you.

If the players have to
cross a lake, spilling a large amount of oil onto the lake beforehand will
provide a nice trap. The oil will float on top, it won’t be very noticeable,
and as soon as they use a [decent-level] fire spell, they’ll set the lake on

To make it hard for the
players to rob their treasure, have it be covered with deadly poison. At that
point, letting the players take [some of] its treasure might actually be to the
dragon’s advantage.

Trap them in the lair, dam
the river flowing out, and watch them drown.

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About Me

I have been a DM for several years, and I was designing home RPG games since my young childhood. I have been a fan of many different types of games (computer, board, RPG, and more) and have designed several for my own entertainment. This is my first attempt to produce game content for a wider audience.