(I made a mistake. The attack on Stones in post #1887 rolled a 15 which is his AC and his Defensive Flourish had expired at that point so Stones is unconscious and his last turn should have been a death saving throw). 

Death Save: 20

That's pretty good for a death save!

(I went back through and I count Stones at 8 HP still. I will go through it again. He seems to have been hit in the fourth round and the first round. I might have missed one so I'll dive back in and see where we're at.)

Quote from rkmobius >>

(Gash and Dog are both flanking WW2 right? Thus melee attacks get advantage? If so Gash would have been able to roll twice for his attacks I think...)

 Oh neat, didn't realize.

attack 1 adv roll 10

attack 2 adv roll 16

(Yeah, I am assuming Stones had full health after the long rest, so I think he should have 8 HP still.)

Tock's bolt slices through the elemental and it proves to be too much. The water creatures cannot hold its form, the water splashing down as it dies.

(Gash lands one dagger hit from before.)

If Water Weird The Second is still up, Dog attacks yet again once, and if it's still up, again (if not, shift the attacks to the remaining WW):

Attack: 20 Damage: 10

Extra Attack: 19 Damage: 13

The water weird splashes down as it dies after Dog's first strike. He darts across the water, splashing with oversized steps, and lands a second blow on the remaining elemental.

Bulwark is up.

Bulwark wheels his maul around in another reckless blow, trying to finish the creature off.

Maul Attack: 26 Damage: 18

The weapon splashes through the water weird, clearly doing some damage, but the misty, dripping elemental stays standing.

Stones is up!

Stones sways, thinking he’s about to pass out from the water weird’s abuse he then gets ahold of himself and, forgetting his Common in the heat of the moment, spits out in Tabaxi “Mreow thpt thpt hack!” and casts Vicious Mockery once again. 

Damage:5

Can Dog speak as a free action to the elementals, "what do you want? why do you and your kin attack us?"

Yup. There is no response, though. (They don't understand common! ;)

WIS(14) save: 3

The water weird pulses so hard that water sprays off of it. It sways like it is drunk, dripping and barely able to hold together.

Gash is up!

Gash being pretty far from the last WW summons more fire  

Flaming sphere slam 5

Fire bolt Attack: 15 Damage: 17

DEX(13) check: 13

Gash's fire bolt turns the elemental to steam, leaving only the soggy, out of breath adventurers left in the flooded room.

(Combat has ended!)

Stone will move around the room to see if anything is in the water. 

Investigation check: 17

Sloshing around in the thigh-deep water, Stones is not able to find anything of value. It seems the elementals were bound to this room merely as another danger of the maze.

"I guess I should some other spells other than fire..." Gash sighs and tucks his daggers away. "shall we continue exploring?"

"Good idea Gash, and yes I'm guessing they didn't seem too scared of fire. Maybe we will fight some kindling golems and you will be our superstar!" Dog says, breathing heavily. "Does anyone need a rest? If not, let's keep going. We've already been away from Nev and Genny for too long. Stones and Bulwark, I would tell you more about them and why we need to find them so badly but I'm honestly not sure who is listening, and how much our captors know. I will tell you more when it is safe but rest assured it is very important that we find them again."

Dog peeks into the southern entrance to the water room while the others decide if they want to rest more.

Stones shrugs “Friends are friends. That’s the only reason you need.”