The Primal Master flickers out of existence (y'all will not let this guy catch a break), disappearing to some forgotten bleak demiplane.

The disintegrate flies forward, another crackling green ray of eldritch atomization hurling towards the Divine Master.

Dex Save: 23

The Summoned Celestial swings with their angelic mace. Their first attack lands true, smiting the fallen angel like form of the divine master for their sins. The second attack, however is parried by the oozing psionic sword.

Ruins, GO! (lets see what you can do now that you're all set up)

Ruin lets out a mechanical laugh... he will now pay back the 'Divine Master.'

He strikes twice with his greataxe

Greataxe:
Attack - 26; Damage: 17 (magical slashing)
Attack - 33; Damage: 22 (magical slashing)

With his bonus action, Ruin casts a quickened Booming Blade, striking the Divine Master a third time with his axe, but the third attack crackles with thunder.
Attack - 36; Damage: 18 (magical slashing) + 13 (thunder). If the Divine Master willingly moves before the start of Ruin's next turn, he takes an additional 16 thunder damage

Ruin's attacks all land, a furious onslaught of power and thunder which sends the Master reeling. 

Arcane Master's Turn!

With a swing of their blade, moon runes appear on the Master's metallic skin. Their blade warps and grows, until it is in the shape of a large crescent moon, similar to an oversized sickle. A cold emanates from them, and suddenly, frost coalesces in the air, forming in the shape of guess what? a crescent moon! The frost moon shoots out towards Wripers. Make a DC 22 Strength Save or:

The Arcane Master swings their blade, slashing at the party

Sword attack #1 VS. Wripers: 15 to hit, 25 slashing plus 20 cold damage

Sword attack #2 VS. Amari: 17 to hit, 24 slashing plus 19 cold damage

Wripers, then Evelyn.

Natural one! That means the second sword attack has disadvantage, so I'll roll that real quick: 20

[First Save Failed, successfully rerolled w/ Zealot trait]

Whether through dumb luck, skill, or divine intervention, the little kobold avoids everything, coming out clean on the other side. 

With a vicious, wicked little snarl, he swings his hammer at the Divine Master like some demented wrecking ball, striking twice with quick succession.

[First swing, to hit: 18 Damage: 34 (14{+16<+4>})]

[Second swing, to hit: 33 Damage: 18]

*now, before I take my turn… do you think the divine and Arcane masters have skeletons?*

Amari (who cannot catch a break!) must make a DC 21 CON save to maintain concentration on her banishment. If she fails, the Primal Master reappears in the space it left or in the nearest unoccupied space if that space is occupied.

CON save (w/ advantage from War Caster feat): 27

Oh god. I know what Evelyn is about to do. And the answer is yes. You can do the thing

Wripers's vicious strikes slam into the Divine Master, who tries to parry the first but fails, and is blindsided by the second heavy swing of the hammer.

Evelyn, GO!

Evelyn looks to the hand of Vecna, then to the divine master. She takes a deep breath and whispers a quiet prayer to the lord of the rotted tower.

She leaps towards the divine master and tries to slash at them, aiming for exposed skin. Any amount will do, just so the magic can take hold. The air around her quivers with magical energy and the hand of Vecna is twitching and clawing by itself, eager to take the life of this celestial… being once and for all.

she uses bones to Jelly. (Yes, weird name but that’s basically what the ability is called and it’s ungodly powerful)

to hit: 26

on a hit, the Divine master must make a DC 18 constitution saving throw. On a failure, it drops to 0 hitpoints instantly as its skeleton is liquefied.

Unless circumstances change significantly, Evelyn will do this again next turn, moving on to the Arcane master once the divine master falls.

Oh. It can be used infinitely. Watch me roll a two on the save and fail.

Con Save: 16

Oh well, better luck next turn.

Edit: OH WAIT DOES ANYONE HAVE SILVERY BARBS?

Well. It appears Ruin does. If he wants to, he can cast it.

That appears to be a no. Continuing on:

The Primal Master doesn't get a turn, as they are banished.

Amelia, GO! (you are still up in the air on your flying carpet. Both possible targets are in range.)

(You can only use Silvery Barbs... or any other reaction... only once in a round. Ruin already did that to turn the critical hit against him into a miss.)

Oh yeah. Huh. Well, Evelyn can try again next round. And I assume once the Primal Master gets back from his vacation, she will once again make sure he can't do squat.

Quote from Raccoon_Master >>

Oh yeah. Huh. Well, Evelyn can try again next round. And I assume once the Primal Master gets back from his vacation, she will once again make sure he can't do squat.

 *oh yeah ha The Primal master is still being petrified. Do they still need to make saving throws agains the spell while they’re banished?*

Quote from Mister_Whisker >>

(You can only use Silvery Barbs... or any other reaction... only once in a round. Ruin already did that to turn the critical hit against him into a miss.)

 *gah, i missed that, sorry.*

Huh, it does. I'll roll that Con Save: 15.

Amelia, time to blow some stuff up. Or shoot it.

Quote from Raccoon_Master >>

Huh, it does. I'll roll that Con Save: 30.

Amelia, time to blow some stuff up. Or shoot it.

 Amelia hums to herself, sat c4oss legged on the carpet as it raises another 30ft into the air (total of 110) to male sure she's out of reach of the any possible harmful effects. Aiming her rune rifle, she mumbles an incantation and casting chilling touch at the celestial being:

19 to hit, and 22 necrotic + 8 force. If hit they can't regain hp

25 to hit, and 16 necrotic + 2 force. If hit they can't regain hp.

The Divine Master? I'll assume that's the one you are referring to.

The Divine Master is struck by two powerful blasts, both dealing solid hits. *calculating how much damage this thing has taken*. The Divine Master is bleeding and severely damaged, haven taken the brunt of the onslaught of the party. A few more good hits should do it in.

Divine Masters Turn!

The Divine Master summons the remaining vestiges of their power, and chaos matter swirls around them. The psychic sword disappears, and the Master waves their hand, a crackling spear dripping poison appearing in their grip. With a shout, they slam the spear onto the ground, causing a magical shockwave for most likely the final time. Ruin and Wripers, make a DC 21 DEX save or:

 Using the handle of their spear, the Divine Master sweeps their spear-like blade, which is long and sharp enough to cut through bone.

spear attack #1 VS. Wripers: 12 to hit, 14 Slashing plus 3 poison

spear attack #2 VS. Ruin: 12 to hit, 14 Slashing plus 10 Poison

spear attack #3 VS. Amari: 22 to hit, 19 Slashing plus 3 Poison

spear attack #4 VS. Kass: 11 to hit, 20 Slashing plus 5

Amari, then Kass, then Ruin