Flooding

[SpacemanR]

So I am working on a quest that involves a hideout under a lake. An interrupted spell during the death of an evil wizard leads to the ceiling cracking....which begins flooding the dungeon. To go along with the flooding, I have made some flooding specific changes:

Movement: as the dungeon progressively floods, movement is made with a -1, -2, and so on as it gets more and more difficult to move.
Fighting: across the board -1 to attack rolls down to a minimum of 1
Pit Traps: Pit traps are no longer able to be discovered, only tripped. Characters still fall into them and end their movement, but suffer no damage
Monsters: the monsters encountered after the flooding begins (orcs and goblins) are fleeing. They appear at a steady rate from deeper in the dungeon, but do not roam freely. They head to the exit, and only fight heroes they encounter along the way


Any thoughts, additions, etc?

[MonsterMotor]

Could work well, could also be deadly or lock up the game. You may look at the Dread Moon Quest 1, which also has flooded corridors, and at the icy river from the Frozen Horror for some comparison.

[Malcadon]

Pit Traps: Pit traps are no longer able to be discovered, only tripped. Characters still fall into them and end their movement, but suffer no damage

That sounds like some nasty undertow. They type that would also pull in adjacent figures and do some damage through drowning.

I can also see squares where water is rushing down from the sealing making movement towards it as difficult terrain (2 MP per square), and moving away from it could result in a slid akin to the Ice Slide from the Frozen Horror.

If you are using Abominations instead of Fimir, this is a great time to use Wandering Monster Traps.
Searching: "As you search the water, you see something hidden in the water."
Disarming: (roll Skull to disarm; no Tool Kit required): "Poking at the thing ahead of you with your weapon, you feel something before you that starts to react. As it jumps out of the water you thrust your blade into its breast. It falls dead into the water. Damn these Abominations!"
Triggering: "As you were wadding though the murky corridor, you feel a rush of water at your feet, and before you can react, something rise out of the water and strikes!" (places an Abomination nest to the Hero and make an attack)

I just came up with this: "You find a pile of dead orcs and goblins in the corridor. In a panic to escape, some fell over causing others to trip and they were all pinned to the floor and walls as more and more tried to move over them until they were pinned to the ceiling. Crushed and drowned, their corpses now dam up the flood waters and waters slowly flows though the bodes You may, with an action, clear this obstruction. But if you do, you may take on more water than you can handle."

If you want ideas used in official Quests:
(Note: there is no spoilers listed)

In The Spirit Queen's Torment, there is a Quest that is totally flooded, so the Heroes must swim. While swimming they move with an extra Movement Die. They are also fitted with some form of water-breathing so they cannot drown.

In Rise of the Dread Moon, there is a Quest set within a sewer with the following Rules:

Waterways are marked blue (actually cyan) on the map. Heroes cannot search for traps in waterways and rolling doubles on the red movement dice while in a waterway will cause a hero to fall and potentially be dragged into one of the pit trap drains. The pit traps in waterways cannot be disarmed but are obvious hazards that heroes can see without having to search.

Pit Trap Drain: If a hero rolls doubles on the red dice for movement while in a waterway, they are unable to take their movement and are instead dragged toward the nearest pit trap by one space per the number listed on one die (on double 3s, they are dragged three spaces; on double 5s, they are dragged five spaces, and so on). A hero can be dragged through spaces occupied by monsters and other heroes but cannot end their turn on them. If a hero’s dragged movement would end on an occupied space, that movement instead ends the space before. If a hero is fully dragged onto the pit trap square, they stumble into the pit and the usual effects of a pit trap take place.