Vazo'yn finds a bundle of threads of fate and pulls on them with all his might, but this ability is new and unpracticed, and in that pull, several possibilities pull into focus at once. A shifting of reality happens and it almost looks like it will work, but the desperate, unsubtle pull causes the lattice of possibilities to collapse and reality falls back into place. A simple glitch in the Matrix. 

Vazo'yn watches a rewind of half a second of time before the shark repeats the exact bite, sending out a jet of crimson into the water, illuminated with the soft, silvery glow of Ylistopus' spear and Randa's quiver. 

DM: I occasionally like to drop snaps of the rolls when things are getting dicey as a reassuring measure. 

As the blood bloom dissipates, Randa is shaken free of the jaws of the Moonshark as it releases to spin around. Somehow, she remains whole, aside from some minor cuts, and is covered in keratin-like plates of earthy colors, which begin to fade slowly into nothingness. To offer an answer to all the silently questioning eyes upon her, she holds up the horizonback medal, which had been used just in her final moments, magically rebuffing the life-ending bite. 

DM: Everyone else, it is your turn. 

Joy’s breath catches as Randa emerges whole, the gleam of the horizonback medal still burning in her mind’s eye, washing away the helpless terror that had nearly broken her heart. Her vision blurs with tears, but the relief is sharp and fierce, coiling into guilt that she hadn’t been the shield in her friend’s place. She steels herself, whispering inwardly that she will not fail them again, not when they’re so close. Feeling the waters shiver against her skin as her oath stirs, she surges forward, armor dragging like an anchor made of faith, and swings with all her weight at the Moonshark, driving for the cavern wall to batter it senseless and keep its hunger from finding Randa or anyone else again.

Bonus Action: Channel Divinity, Fury of the Tides 

 Action: Longsword to hit 17-2= 15, damage 8 slashing + 3 bludgeoning if it hits the wall.

Ylis moves in front of the shark staying 10 feet distant and begins to wave her tentacles in its face. Hopefully all the bits waving about can cause a distraction. While the octopus body seems immensely strong compared to her bunny body, she feels the others could hit the shark harder if she HELPs.

HELP action to the next attacker. 

 DM: Joy Attacked with Disadvantage and the shark still glows with Advantage (which cancels out the underwater Disadvantage that mundane attacks suffer). I am fine letting her reroll that, or someone else can get the Disadvantage-cancelling effect. 

This is in addition to the Help Action that Ylistopus is going to give a separate attacker. 

((Someone else can use it since Joy has the -2 from exhaustion.))

((Vazo'yn doesn't get much from advantage on attacks. Randa or Joy would probably be best.))

"Kill it! Disable it!" Vazo'yn yells, his urgent voice muffled slightly by the turbulent waters disturbed by the shark's violent attack.

He focuses his attention on the shark, once more trying to assail its mind with haunting, distracting whispers. He is desperately trying to prevent it from mauling on of his friends again.

Action: Vicious Mockery. DC 13 wisdom or 4 psychic damage and disadvantage on next attack.

Seeing Randa free, Berk does a quick check to make sure his medallion is still around his neck, then begins a spell. He waits a moment as Ylistopus taunts the shark, then sends for a bolt of light at the shark.

bolt: 8/17  Radiant Damage: 18

[I believe with Ylis adv and underwater disadv it's a straight roll of 8, but i rolled twice in case I'm wrong]

DM: Casting does not suffer Disavantage underwater. Melee Weapon Attacks (piercing weapon attacks excluded) and Ranged Weapon Attacks do. Therefore you get the Advantage from the glow and 17 hits. 

Someone else can still get the Advantage from Ylistopus' distracting Help and THEN there will be another buff to someone else for the Guiding Bolt Berk just cast. 

[fixed the typo ... tooltip not found]

((Randa also has advantage from Vazo'yn's Silvery Barbs))

((Ok, I'll reroll for Joy. Nice, 15! Hopefully that hits.))

Joy surges forward. The beaming, happy young woman's face now replaced with a steel-eyed glare that is as cold as the blade in her hand. She feels light in the water, almost as if the ocean has picked her up and carried her forward, urging her to protect her friends.

The blade is drawn down the body of the shark in a long gash, and the shark squirms in protest as the ocean itself has turned against it, battering it against the cavern wall.

The glow of the shark fades immediately after, but then Berk’s own divine fury blasts the shark with a new glow, radiant gold now instead of silver.

Meanwhile, Ylistopus attempts to distract the shark with an interpretive dance in octopus form. 

DM: Randa is the only one we wait for. 

( Just checking. Does Randa still have hold of the amulet?)

DM: I will say yes because you were not knocked unconscious, but the text does not list pulling the rope off as an option and narratively, that makes sense because the shark is hostile. You can attack the rope that fixes the Eye to the shark though. 

Randa began sawing at the rope with her scimitar.

( If it comes loose, she will retreat 45' with Longstrider back the way they came in, risking AoO and aim her bow at the shark for next round.)

Attack: 16 Damage: 6

DM: When getting Advantage and Disadvantage on the same attack, they simply cancel out and there is no stacking. Regardless, that is a miss! 

Randa tries to stabilize herself just enough to start sawing at the rope, but the creature wriggle and turns about so much that it is impossible to get the leverage needed to cut the rope.

The shark responds to her assault by trying to clamp down on her head, but nips only at the water.

On the far side of the cavern, a figure is seen on the periphery of the light shed by the spear and quiver. Ayo. The shadows are deep at this range, but she looks to have seen far better days. Lacerations adorn her form and she looks like she would rather sleep than anything else at the moment. Maggie’s face turns the corner of the tunnel, now haggard and sporting a massive circular bruise on her face. As she pulls herself through the cramped tunnel, Maggie's leather armor is also torn open at the belly, and a large circular hole now exposes highly developed abdominal muscles.

Ayo calls back to her team. “Those rotten elders sure like the big animals. Another octopus, this one isn’t as big, but it has a big shark with it. We do it like we did before. Maggie will take out the octopus, I got the shark.” She looks to the Fellowship and a tired grin spreads across her face. “You might have gotten ahead of us, but the heroes are here to help you out of a jam.”

DM: Ayo and co. will follow your collective turn, which is now!