Gnoll camp
The text said that on the gnoll side of the river the ground is not flat. But it doesn't say what that implies.
Is it difficult terrain ? Uneven terrain ? Both ?I would go with both (to actually use the Gnoll "bonus" against difficult terrain. Which would be useless otherwise because everytime there are gnolls, no difficult terrain is indicated). What do you think ? What DC would you use ?
Also there is no indications about how many squares are concerned. Is it just the first square along side the river ? More ?
I think in the Bestiary, under the "Mountains" section, it says that a slope is difficult terrain going up, and normal terrain going down. I assumed that all of the terrain on that side of the river was sloped.
Water/Earth Elemental
They are said to attack as soon as the PCs are in 1 movement range.
But the two elemental are somewhat far from each others.So, if the Water attack, does the Earth also attack or does it also wait for the PCs to come to his side ?
Speaking about the Earth Elemental. How is he supposed to fight ? I get that the intent is to make the players climb on the rock to avoid the water one, and then the Earth would burrow, travel to the rock where the PCs are and attack. Giving his speed that would take one round, maybe two.
But as it is written, if the PCs are in the water, he is supposed to somehow ... swim ? An Earth Elemental ? Sure, that would be hilarous but ...
I had each elemental attack separately, but I think it would work better if they both rolled initiative at the same time. Makes for a more dynamic battle, I think, with both the water and the rocks being dangerous in their own ways. I had the earth elemental burrow between the rocks, which took several turns of movement, but made more sense to me, since the earth elemental takes penalties when it's not touching the ground.
Fire / Air
I don't understand the room. The ground below the balcony is also a dome ?
Si what happens if someone want to go down (being suicidal) ?
He leap ? How hight is it ?Is it uneven ? I guess it is, but there is nothing written. What DC would you use ?
So the Fire Elemental is also affected by that ?Or would you make the ground flat and only the wall shaped like a dome ?
I ruled that the platform was only 2-3 feet tall, so it's easy to get down onto the floor, but harder to get back up. I didn't call for any balance checks for standing on the floor (my players were already taking a beating from the damage for standing next to the lava and the fire elemental's persistent damage). It would be plausible to rule the floor in this room as uneven ground, though.
I placed the fire elemental in the lava in the center of the room, which would be flat, even in a bowl-shaped floor.
Gnoll Camp:
It's a camp, so should be on flat ground (especially if there's a competing flat ground option right across the river).
I think just the lip is supposed to slope up, the better for the gnolls to jump off of to cross & engage when the party's starting to be separated by the river & current!
Water & Earth:
Once there are lights in the room, the Earth Elemental would likely burrow to within one movement below the party, waiting for combat to start. If the party all goes in the water...well, that'd be foolish so there should be somebody on shore for it to attack, maybe whoever has the rope holding the swimmer(s)!
Fire & Air
The room is a hollow sphere with a pool on the bottom & a ledge w/ opening on the side, midway up. So the fall isn't so far (10'-15'), but yes, the ground would be uneven off the ledge, though I wouldn't make it so PCs tumble automatically down the slope into the lava!
The elementals attack immediately, so it's unlikely a PC has jumped in w/o scanning for danger first. The biggest threat is if the Air Elemental starts pushing people off the ledge and/or into lava. Yes, the Fire Elemental has to navigate this too. It's a DC 18 to climb to to the ledge, which is hard for the F.E., so it might wait for PCs to be knocked down to it.
DerNils,
The Air Elemental does not Shove (as you noted, its Athletics is too poor to do that), it Pushes, which is automatic (w/ a successful Strike then a Push action).
Once the A.E. has pushed somebody off the ledge, the Fire Elemental can engage w/ it (if it hasn't managed to climb up yet). The A.E. can tempt somebody to come to the edge to strike it (maybe after a Disperse so it's not so obvious), then circle around to knock them off.
ETA: And yes, there's no incentive to enter the deathtrap, nor the water one either. Veteran players instantly recognize this. Funnily enough, this may cause them to assume a reward awaits too!
Minor Air Elementals don't have Push. Only Lesser and higher level ones do.