Even though he does not manage to jump over it, the poison trap only has a minor effect on the dwarf.[sblock=Roll]Poison vs. Fort (1d20+7=12)Miss!
BUT - any creature that enters the trapped area automatically takes 5 poison damage. You don't get hit with extra damage from the attack, but you did move through the cloud, so you take the minimum 5 damage.[/sblock]As Sledge comes to a halt at the end of the hallway, he peers around and sees that the room widens into a 30 ft. wide room, with a staircase leading up into darkness on the right side. Further into the room, he can see a few walls and an open doorway (S7-S8) flanked by two windows that reveal several piles of rubble and at least one broken statue lying in the floor.
GM:
Only Sledge can see this - the others can see only as far as row "V".
Actually, one correction to the above - Brocc, Nicodemus, and Mallick can't see past the poison mist. From the stat block for the trap: "The mist provides concealment and blocks line of sight..."