Infiniti2000 said:
Well, the AMF will cancel out the magic holding the water in place, Goolpsy.
As for more to work, I really can't without revealing spoilers, but I have no other details about the magic holding the water, so your guess is pretty much as good as mine. Is there a spell that might be in effect, perhaps? Dunno, but I've already decided that confronted with an AMF, it will rush out and now I'm just curious how to run it. Thanks for your help though.
Oh yeah, one more thing. Can you teleport/dim door into water?
What an interesting situation! This looks like a complicated and, potentially, very lethal situation for the PC's.
Here's some suggestions covering most (I hope) of the issues involved:
Let's assume that the door is magically held (like arcane lock) and bursts open as you say - i.e. that the force holding back the water does not return if the guy with the AMF going gets swept away.
Decide where characters that get swept away end up, and, in particular, what the difference in height is between that point and initial water level in the water room. When the water is released, it will hit everyone with considerable force. I would use the rules on Falling from the DMG p. 303.
From a purely physics point of view (assuming your world has normal physics), the impact of someone falling into water and a wall of water falling on them is the same, and depends only on the difference of height between the character and top of the water-filled room. Per the DMG, the impact of the water would be no damage for the 1st 20 feet, 1d3 damage (nonlethal) for the 2nd and 3rd 10 feet, and 1d6 damage (lethal) for each additional 10 feet difference.
Decide if the door simply opens or is broken off its hinges. It's reasonable to assume that a solidly built door can normally hold back the water pressure if it's built for that purpose. If the door breaks away, use the rules for Falling Objects to determine how much damage to apply to the first character based on the vertical distance between them. If it's a heavy door (>100 lbs) it should do 1d6 damage per 20 feet fallen. (This probably won't happen if it's within the radius of the AMF.)
Give each character a strength check (a very difficult one) to avoid being washed away. I'd suggest something like DC 20 + damage (lethal+nonlethal) inflicted by the water's impact. There's probably no way to avoid this damage, or even to remain in place for that matter, without extraordinary means.
Those characters washed away will probably (totally a DM call according to how nasty you want this situation to be) take damage from buffeting as they are caught up in the flow, maybe something like 1d4 (nonlethal)+1d4 (lethal), Reflex 15 half, per 20 feet falling distance for banging against each other, the stairs, etc. on the way down. If the characters are washed forcibly into a wall or around a corner, apply falling damage according to the (vertical) distance they fall equal to normal falling damage (1d6 per 10 foot dropped), applying all the normal rules for any abilities the characters may have to mitigate this damage (tumble/jump checks, etc) at each impact point. There should be no extra falling damage if they are simply washed down into a large pool, since the water itself (both flowing and in the pool) will cushion their fall significantly.
Example:
The door is at the top of 20 foot (vertical) flight of stairs connected by a 90 degree landing to another 20 foot (vertical) flight of stairs, which lead up from a 20' x 20' room. Assume the door slams open but stays on its hinges.
The marching order is the Rogue at the door, the wizard (with AMF going) right behind him, and a fighter on the landing.
The water rushes out dealing 1d3 (nonlethal) damage (30' height difference) to the rogue, forcing a DC 22 (avg) str check to stay in place. If he stays in place, he may be hit with the creature from the room (if it can fit through the doorway) doing appropriate normal falling damage to both of them. If washed away, he takes 2d4 (L) + 2d4 (NL) (Reflex 15 half), from tumbling down both flights of stairs, 1d6 (L) + 1d6 (NL) damage from being slamed into the wall at the corner landing, and another 1d6 (L) + 1d6 (NL) damage from hitting the wall of the room at the end of the fall.
Since the wizard is within 10' of the rogue, he takes the same damage. i.e. potentially 1d3 + 2d4 + 2d6 (NL) and 2d4 + 2d6 (L) damage.
The fighter standing on the landing takes 2d3 (NL) + 1d6 (L) (50' height difference) damage from the water's impact, requiring a DC 27.5 (avg) str check to stay in place. If he get's washed away, he takes 1d4 (L) + 1d4 (NL) damage from the tumble down the bottom flight of stairs and 1d6 (L) and 1d6 (NL) damage from the impact into the opposite wall of the room at the bottom.
I wouldn't be surprised to see all of the water drain out of the top room in one or 2 rounds (6 - 12 seconds). Depending on the size of the room at the bottom, drowning may be a real issue here, especially if anyone has been knocked unconscious beforehand. Then there's the issue of the water creature, which probably will be washed down with them (and suitably roughed up) and won't be very pleased to see its home ruined.
Regarding:
Can you teleport/dim door into water?
So far as I know, there are no rules prohibiting this. I'm pretty sure that it works everywhere on the Elemental Plane of Water, for example. For flavor, you might use the displacement (house) rule: Someone teleporting from air to water leaves behind a (human-shaped) volume of water that rapidly collapses.
I hope this helps and gives you some ideas on how to adjudicate this situation.
