Gerrard:

Stealth:  14

Initiative:  14

Initiative:  11

Stealth: 7

Peri:

Peri whispers to Kei, "Guard post ahead. Might wanna summon your crab so you can see." To Boko, "Need to split up. If you're goin' in, go to the far side of the guard post and I'll try to meet you there."

He quietly makes his way along the corner of the ceiling into the guard post. (Stealth: 21)

((I'll leave it up to Kei and Boko whether they also go on.))

Boko taps Peri on the shoulder once and then moves along the ceiling stealthily to the far side of the guard post.

Stealth: 32

The others in the torture room brace for a fight. Only Kysh's sea lion takes a cue from Gerrard and Qivys and tries to get the jump on the intruders.

Stealth:
Gerrard: 14
Qivys: 7
Kysh's Sea Lion: 7

Initiative: 
Gerrard: 14
Qivys: 11
Oceanus: 17
Kysh (Triton):  11
Kysh's Sea Lion: 14
Borgas: 11

Kei 

Now alone as his two guides move into the guard house he takes Peri's advice. He calls Krill back from his pocket dimension. With his mind he asks it to move carefully into the room. He alternates between watching through Krill's eyes and moving, cautiously entering into spaces far away from the sahuagin. 

Stealth 38

And only the sea lion manages to surprise the three sahuagin entering the room. 

Sea Lion Bite Attack vs Sahuagin #1 : 15. Hit: 13 piercing damage.
Sea Lion Bite Attack vs Sahuagin #1: 26.  Hit: 10 piercing damage.
Sea Lion Claw Attack vs Sahuagin #1: 25.  Hit: 13 piercing damage.

Sahuagin: Initiative: 16

The sea lion shreds the leftmost sahuagin, leaving it rather bloodied but still up.

With both fin-like hands, Borgas rams his spear, twice, at the rightmost one. 
Spear Attack #1 vs. Sahuagin #2: 14. Hit: 7 piercing damage.
Spear Attack #2 vs. Sahuagin #2: 20. Hit: 6 piercing damage.

Only Borgas' second strike manages to find its mark.

The sahuagin immediately engage:
Sahuagin #1 Spear Attack #1 vs Sea Lion: 24 Hit: 4 piercing damage.
Sahuagin #1 Spear Attack #2 vs Sea Lion: 23  Hit: 8 piercing damage.
Sahuagin #1 Spear Attack #3 vs Sea Lion: 18  Hit: 7 piercing damage.

Sahuagin #2 Spear Attack #1 vs Sea Lion: 9  Hit: 5 piercing damage.
Sahuagin #2 Spear Attack #2 vs Sea Lion: 18  Hit: 10 piercing damage.
Sahuagin #2 Spear Attack #3 vs Sea Lion: 12  Hit: 10 piercing damage.

Sahuagin #3 Spear Attack #1 vs Borgas: 22  Hit: 10 piercing damage.
Sahuagin #3 Spear Attack #2 vs Borgas: 25  Hit: 5 piercing damage.
Sahuagin #3 Spear Attack #3 vs Borgas: 24  Hit: 10 piercing damage.

Crit vs Borgas: +5 

The sea lion is injured, but Borgas is badly punctured.

Gerrard and Qivys may act next.

Initiative:

√ Borgas
√ Sahuagin
Gerrard
Qivys
Sea lion
Oceanus
Kysh

Meanwhile, little Bokotopus glides unnoticed over the heads of the sahuagin, while Peri peers invisibly around the corner.

 At the south end of the east wall, a bronze gate bars the exit to the east. Beside it, on the east wall, is a bronze mechanism of chains, wheels, and pulleys. Next to the mechanism, a wooden peg has been driven into a crack in the wall. A rope, ascending through a hole in the ceiling, is lashed to the peg.

A total of eight well-armed sahuagin occupy this room.

Peri can see that installed in the ceiling of the short corridor leading south is a large net.

Qivys will move close and attack the closest Sahuagin with his battle axe.

Hit: 20

Damage if hits: 7

Upon a hit Qivys will use a bonus action and expend a 3rd level spell slot to Divine Smite.

Divine Smite Damage: 22

Gerrard:

With his hands full, Gerrard decides to forego the grapple for right now and slides through the door to the southwest, engaging the trailing sahuagin.  Suddenly, instead of attacking that sahuagin, Gerrard launches a flurry of stabs at the one in the room just savaged by the sea lion.  if he succeeds in taking it down, he tries to shove the trailing sahuagin into the room (in its place) and shut the door...

Action to Attack 2x with the rapier and Bonus action to attack with the main gauche:

Rapier:  Attack: 15 Damage: 10

Rapier:  Attack: 18 Damage: 10

Main Gauche:  Attack: 10 Damage: 7

Action Surge:

Rapier:  Attack: 12 Damage: 8

Rapier:  Attack: 13 Damage: 13

As soon as the sea lion foe falls (if it does), he switches to shoving the adjacent foe into the room and trying to close the door behind them--ignore subsequent attack rolls above if they are not needed and use the shoving below:

Gerrard lays into the injured sahuagin with a flurry of attacks from behind. But it takes everything he has to finally take it down. These things are tough. One down, but he has nothing left to deal with the third sahuagin.

Qivys cleaves into the second sahuagin with burst of divine radiance. It howls with fury.

Gerrard:

”Get the last one in and shut the door!” urges Gerrard quietly but forcefully.  He has no idea if the arena noises will cover them or not, but he is worried about the alarm being raised the longer this battle goes on…

Unable to follow Gerrard's instructions, the massive sea lion moves in on the second sahuagin, tearing into it with the advantage of the proximity of its new pack.

Sea Lion Bite Attack vs Sahuagin #2: 14. Hit: 10 piercing damage.
Sea Lion Claw Attack#1 vs Sahuagin #2: 17. Hit:15  piercing damage.
Sea Lion Claw Attack#2 vs Sahuagin #2: 24. Hit:15  piercing damage.

Oceanus, however, is able to slip around the back of the sea lion to attempt to engage the third sahuagin in the doorway.
Oceanus Trident Attack #1 vs Sahuagin #3: 9 Hit: 3 piercing damage.
Oceanus Trident Attack #2 vs Sahuagin #3: 16 Hit: 3 piercing damage.

Kysh, the farthest from the door, is only able to circle around and get into position near Qivys.

The second sahuagin is badly mauled by the sea lion and is barely up. The third sahuagin receives a minor wound.

-- Top of the round --

Borgas takes another stab at the second sahuagin with a two-handed spear thrust:
Spear Attack vs Sahuagin #2: 9. Hit: 4 piercing damage.

The second sahuagin, barely standing, stabs desperately at the sea lion:
Sahuagin #2 Spear Attack #1 vs Sea Lion: 23. Hit: 8 piercing damage
Sahuagin #2 Spear Attack #2 vs Sea Lion: 8. Hit: 7 piercing damage
Sahuagin #2 Spear Attack #3 vs Sea Lion: 11. Hit: 11 piercing damage

The third sahuagin carefully disengages and retreats quickly south and then east - around the corner and out of view. 

(Borgas misses badly; the sea lion takes some serious wounds from the spears but is still fully engaged. The sahuagin can swim pretty fast.)

Gerrard and Qivys are up.

Peri:

Peri carefully crawls along the ceiling to examine the rope going to the net. He'd planned on simply tying a knot around a pulley, but the small hole makes this impossible. Well, a small hole offers other possibilities. He removed a piece of chalk from his belt pouch and holds it in his mouth. Then he very carefully, slowly pulls any slack down through the hole. He teased the strands of the rope apart, loosening the twist, until he can fit the piece of chalk into the strands. This creates a lump in the rope too big to fit through the hole. He begins wrapping the lump with some string so that the chalk won't fall out. He lets the weight of the net pull the lump up into the hole so that it wedges in place.

Then he crosses to the far side to try to find Boko and Kei. Damn, but that octopus is hard to find! He has to feel along the corner of the ceiling. He didn't see the little creature until his hand landed on a squishy tentacle.

Gerrard:

”We can’t let him warn the others!” calls Gerrard as he swims away swiftly thanks to the magical aid of his Mariner’s Armor.  He follows the escaping sahuagain, getting tantalizingly close (hard corner makes it 35 feet instead of 30 if I read it right), then dashing to get as far as he can on the far side of it.  After he passes it, Gerrard sheathes his Main Gauche in preparation for a Grapple attempt should the creature keep coming his way.

OOC:  Risking AOO’s to try and block the creature’s escape.