[Nub was trying to take some attention off Nate, so he can move away if needed.]

You can administer the potion from the square next to Nate and avoid Opportunity Attacks.  However, if you want to enter Nate's square and then leave in order deliberately to provoke Opportunity Attacks, you can absolutely do so.

[Yes, if that is ok. Nub will make a face as he does so, hoping that they will strike at him, allowing Nate to move away if needed.]

Moonbeam damage: 17

Nate's consciousness returns as he gags and chokes on the red liquid. He looks up into Nub's torte eyes, and regains his bearings in the moment. He senses that Nub is putting his life on the line for a split second for Nate to escape this current situation, along with Soar, so he takes that opportunity to do just that. 

He'd rise to his feet using half of his movement, then disengage and get as far as he can from the cultists. Not sure if he's still in melee range of the bottom cultist or not... depends on where he regained consciousness.

Nate, you are able to move out of the cultists' reach, to behind where Jalt is standing.

The two cultists now focus their attacks on Soar:

Attack: 12 Damage: 9
Attack: 24 Damage: 7
Attack: 22 Damage: 5
Attack: 19 Damage: 6

I believe that last blow brings Soar down, is that right?

Jalt, Soar and Nub are up.  Soar, if you are unconscious, you can wait until after Nub and Jalt have gone before making your death saving throw.

You see two cultists, both badly wounded; there's no sign of Borngray.

Yeah the third hit takes her down.

Since Borngray is long gone... Jalt runs towards the downed Soar and points at cultist 1 and casts Sacred Flame Dex 14 save 12 damage and with his bonus action will cast Cure Wounds at lvl 3 on Soar for 13

Cultist 1's DEX save:  6

Cultist 1 is really badly hurt, but just still on his feet.

(As that's a bonus action it would be Healing Word - I'll roll for it 9.  Soar,  you awake - you are prone, but can take your full turn now)

Soar and Nub are up.

Nub will cast create bonfire at Cultist 1 for 6 damage, Dex 14 save. If Cultist 1 does not move or anyone else enters that square, they will need to make a Dex 14 save or take 9 fire damage.

Cultist 1's DEX save:  6

The cultist dodges out of the way and avoids taking damage.

Soar is up.

Soar opens her eyes and gets her bearings, rising with a grunt. “Oh that was a mistake,” she says to the two cultists. She swings her sword swiftly, brutally, at the first until they drop and then the second.

Attack: 24 Damage: 9

Extra Attack: 20 Damage: 9

Cultist 1 is down, his neck sliced open by Soar's weapon.

Cultist 3 is near to death too.  He makes two last attacks on the half-elf paladin:

Attack: 18 Damage: 6
Attack: 15 Damage: 9

Utterly without success.  You see defeat in his body language and on his face.

Actually, Nate should have gone before that.  Nate, you're up.  Only Cultist 3 remains (and the unseen fleeing Borngray)

Nate, basically exhausted, will basically run over and stumble/fall onto the cultist, at the same time casting primal savagery trying to drive his nails into the cultists throat.

Attack: 20 Damage: 14

The final cultist falls.  Combat is over, though you have the option to chase after Borngray if you wish.  You stand in what you would guess is Borngray's office, as quiet returns to the castle.

Nub asks the others "I know you are hurt, are you up for chasing Borngray or do you need a rest?"

Soar says “I can go” and she chugs a healing potion on the way. Maybe two.

Nub starts double dashing as soon as Soar says that, back to the stairs.

Potion: 4

Jalt will follow right behind Nub.