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

PLESIOSAURUS: Trapped on the Dinosaur’s Back


Combat rating 3


1 Plesiosaurus (CR 2)

3-4 Bullywugs (CR 1/4)



Combat rating 3


1 Plesiosaurus (CR 2)

2 Grey oozes* (CR 1/2)


* [hiding in the river mud]

Combat rating


Plesiosaurus (CR 2)

3-4 Giant
wasps (CR 1/2)

1 Swarm of
quippers (CR 1)


rating 5


Plesiosaurus (CR 2)

3 Ankhegs
(CR 2)

How to Use – Combat Encounters (difficulty 3)

The plesiosaurus is the dinosaur with the long neck, which D&D has translated into a 10-foot reach. This is understating it, though. In this case, the extra movement comes with eyes, which means that the attack can take place around corners. Have the plesiosaurus stick its neck around the bend in the river, [with a corresponding hill or bush/thicket in the land. You need the players to not be able to see it.] It will have an attack that they can only retaliate against with their attack of opportunity. Attacking from over bushes or thorn thickets will have the same effect.

You’ll most likely have to use this as part of another fight, or they’ll just charge the plesiosaurus. Alternatively, the plesiosaurus is sticking its head through foliage, and on the other side of the foliage is deep water, with no place for them to stand where they can see [and fight] the plesiosaurus. (The plesiosaurus’s long legs let it stand in deep water.)

The other problem with this idea is that there is a strong chance that they’ll retaliate by means of readying actions for when it pokes its head out. You could deal with it by not having the plesiosaurus attack every turn. Or, you can use thick foliage to divide the battlefield into two or more parts, without them being able to see all of the battlefield at once. (While you’ll obviously let them see it all on the battlemap, it means that a readied action will be wasted if used in the wrong area, and of course you won’t have the plesiosaurus always attack the same area.)

Combat Encounter 2 (difficulty 4)

A different idea that should work nicely is to arrange for the PCs to fall into the river (some or all of them.) If they’re on a boat it can get swept over unexpected rapids, it they’re crossing a river one of the stepping stones could prove unstable or slippery, or you could have rapidly rising waters, a flash flood that knocks then into the river, or a riverbank that unexpectedly gives way due to the combined weight of the party.

The effect of this is that they wash downstream, and the first chance they have to catch themselves is when the waters sweep them into one or more plesiosauruses. The bulk of the dinosaurs stop them from being washed further, and they should be able to climb up onto the back of the plesiosaurus without too much difficulty, maybe an action at most.

The problem is that the plesiosauruses aren’t going to like having PCs on their backs. While they aren’t the type to buck the PCs off, their long necks mean that they can attack the PCs while the PCs are on their backs. Also, if the players kill them, the plesiosauruses will collapse and the PCs on its back will be swept back into the river. You might consider placing a waterfall not too far from where the battle is taking place, and/or steep sides to the lake, to further incentivize the players to stay out of the water.

For a more realistic idea, put vicious fish, (such as swarms of quippers) into the water, and make the closest place where they can climb out be some distance away. Most animals don’t like the swift currents that a waterfall causes, and won’t be found in such an area. At the same time, viscous fish like quippers might not be able to bite through the thick skin of a plesiosaurus, or might know better than to try. I chose a waterfall because it’s far more dramatic, but you can choose between drama and realism for yourself.

If the players don’t climb onto the plesiosaurus, you can always have the plesiosaurus take exception to their presence and attack anyway. This will be doubly true if you are using the waterfall, and they have to hold onto the plesiosaurus legs to prevent being swept away.

I should mention that the different ways that you can create this encounter are also different ways that the encounter might run. A scenario where they arrived in a boat, and they have to get the boat close enough the plesiosaurus to pick up their party members, is quite different than one where they are all on the back of a plesiosaurus with no clear way to get off, and different again from a scenario where they are on the backs of different plesiosaurus. Choose for yourself which encounter you most want to run. 

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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.