Gotch will keep back from the door still, his crossbow ready in case anything comes through it, or across the doorway.

 Attack: 9 Damage: 5

Izen comes out of the room and after a moment look, finds her target anf fires the magic bolt into the gatorman's back, setting him a blaze for a moment before fall at Gwazi's feet a sorched corpse. It's easy to deduced the last Lizardman has hightailed it while glowing and poisoned. 

You're  all out of initiative now, what do you do?

Tundra relaxes and dusts herself off as she sees her companions put an end to combat. "Nice job" she says with a slight smile, before going to search the dead bodies for any useful information or item.
As she pats the bodies and flips them from side to side, she'll also try to recall whether she's seen similar creatures in her time in Sigil. (Or if they're just Dragonborns)

Investigation: 9

Tundra examines and tried to remembered. She recall seeing similar Newts in Sigil but they were few but she can't put a name to the body. 

From the bodies, very little could be found and was of real value. They had scales so they had no need for armor and they have little in way of weapons. 

Izen then went to the table and sat down before pulling out the shining silver liquid from before as he looked over at Gwazi gestering him over "hey you're pretty good a spear. Mind if I enchanted it some" he asked shaking the brew a bit

Gwazi smiles at the offer. He has heard of such magics, and it might come in handy. "It will not damage the tip? If not, then yes, please. These lizards are quick, after all." he says, holding a hand against his shoulder. Some blood was still trickling from the wounds he'd taken, but it did not seem to bother him too much.

"Let's find a way out of here as well, huh?"

Gotch will make sure nothing else of importance is in the sorting room, then he will move out into the hall.  Once everyone is ready he will suggest they backtrack the ones they just fought, thinking that might lead to the way out.  (Assuming there are no other doors they come across to look into first...)

Once everyone picked up all their gear, Onyx will start to move down the coridor.

sneak 26

perception 24

Izen let out a small chuckle before walking up to Gwazi with a grin on his face "don't worry about it this stuff is good" Izen said pouring a bit of the silver liquid over the spear before turning it back upright. The bit of liquid poured on the weapon spread out covering the entirety of it causing it to glow a bit with magical energy "ah ha there we go"

Artifer infusion you're spear is now a +1 weapon until I say it isn't to use a different infusion 

As Onyx stealthy makes her way down the corridor until the corridor leads into a swallow ramp leading into a pit area, 10ft high thick stone barricading walls separating Onyx from these spectator area. The barricading wall has 5ft iron bars sticking out of the top. Above the pit you can see tiered seating starting. There's another corridor you can see on the opposite side of you.

A iron bar wall separate Onyx from the pit but Onyx can see a lever next to the iron bar wall. This new arena is brightly lit. 

Rough Map

(There were no other doors, side passages, or anything else?)

It is possible to climb into the spectator area by climb the walls and squeezing between the bars, There's a balacony above one section and several doors on the opposite side. Note the the corridor into the pit is enclosed to climb into specatator area means you need to go into the pit first. 

Gotch takes a moment to cast mage armor on himself.

"Appears we have no other way to go..."  He will comment to the others as he looks at the pit beyond the bars.  "Who wants to be the first through once the gate is opened?"  Gotch is definitely giving the vibe he is not going to be that person.

(Is this the hallway I first went in, with the water, or is it another hallway next to the sorting area we were in. Kind of having trouble visualizing where we are going.)

Seeing the pit, Tundra walks back to take one of the pebbles the gators threw and makes a motion to drop it, half expecting some abyssal creature to jump out of the floor. 
Preparing herself to let go of the stone, she tells herself that it's just a very creepy pit, one that they'll have to be very careful of.
Delaying the inevitable, she turns to the spell casters next to her and says
"So... you guys have no, like.... magical bridges or anything? I mean, I don't want to be like that but, ... It would really be useful if we didn't need to... Like... Go there... Or poke it really..."
She turns at Gotch asking, "I mean, you can make chairs right?  You could make a bridge.... Right?" 
She tries again asking, "I've got some rope... is that anything?".
As she realizes she should probably drop the rock before imagining everything that could be, she finally lets go of the rock and intently looks, from a safe distance what happens.

It's a end of same corridor with the water, there is water dripping from the ceiling everywhere. The corridor was rather long tunnel from between the cage area and this area.

As Tundra drops the rock into the pit and nothing happens. The sound of the rock hitting the ground echo through the empty arena.

Attempt to clarify set up
The Arena is two tiered area. The Corridors is a tunnel that is goes under the seating area. The corridors and pits are same level, only a iron bar wall separate the two. 10 from ground level is the spectator area is. There's also a 5ft high metal fence that lines the seating area. The bars are big enough for you to squeeze through with some effort for most of you. 

Mashed Up Map

(Thanks that makes much more sense.)

Tundra squeezes through the bars and tries to climb to the spectator area.

Acrobatics: 16

(First iron bars to get into pit will open with leveler pull, Tundra would need to climb up then sqeeuze through bars that seperate specators from pit)

Tundra shows of her taxabi agility, quickly jump onto the ledge and squeezes liky only a cat could do. Tundra looks around, seeing several closed doors to the south, a few seems to damaged. To the north is just regal looking balcony overlooking the pit. 

Onyx purrrsues what Tundra the tiefling monk is doing, before following him through the bars.

10 acrobatics.

Gwazi sees the others making their way up, silently praising them for their acrobatics. "Here, help me loop this around the railing." He says, taking the rope from his pack and tossing one end up. Once it's looped around he'll use it to make his own way up and over if he can, then turning to help the others up as well.

Mechanics:

(Would have taken athletics checks as well)

With the rope provided by Gwazi, the task of escaping the pit become a simple matter (no checks needed for rest to climb). One by one the rest make their ways up but in the meantime, there are sounds of explosions and distant screams coming from the southern area (I just using cardinal direction as point of reference is does not reflect real direction). You quickly noticed one of the southern doors is ajar.