So... if we're starting combat, Akkron would try to enter the room (and, by extension, remain comfortably in Clarac's aura), taking up residence in the space up and left to Tyekanik.

If he needs to make that Con save to do so:

20 (rolled in game log) + 6 from Clarac's Paladin aura for 26 (looking at the map, I think Akkron should be just inside of her aura right now).

Same effect, though he can feel it as a magical energy, like a spell that had been cast but had no effect. 

Seeing the devils rushing towards him, lashes out at the devils with his dark powers:

He Glares at Hanaphaen: (Save 18) 

Three Conflagration attacks against the devils on your left

Legate 1 Attack: 29 Damage: 35

Magistrate 1 Attack: 25 Damage: 35

Magistrate 2 Attack: 29 Damage: 35

Hanaphaen appears to hug himself tightly as protection against an unbearably cruel world. He balls up and goes fetal on the floor.

All three flame attacks strike the devils. 

The devils attack Vairae:

Legate 1 Attack: 22 Damage: 25; Attack: 12 Damage: 25

Legate 2 Attack: Attack: 23 Damage: 25; Attack: 19 Damage: 25

Legate 3 Attack Attack: 19 Damage: 25; Attack: 24 Damage: 25

Magistrate 1 Attack: Attack: 19 Damage: 24; Attack: 26 Damage: 24; Attack: 24 Damage: 24 

Magistrate 2 Attack Attack: 15 Damage: 24; Attack: 12 Damage: 24;; Attack: 26 Damage: 24

Abjudicator Attack Attack: 19 Damage: 27; Attack: 20 Damage: 27

Akkron pauses... there isn't a huge amount for him to do in this moment, but he figures he really should help the devils out a little bit. So, he points his finger and casts magic missile at the High Mage for a bit of guaranteed damage (using one charge from his Staff of Power). It ain't much, but it's honest blastin'

Magic Missile damage (rolled in game log)
3 + 5 + 4 = 12 damage.

Khessa shares Akkron's assessment that the Devils could use a little help - she therefore summons a large, disembodied hand.

The hand lunges at the lich to grab him!

[[ OOC: Khessa upcasts Arcane Hand with a 6th level slot. She chooses the Grasping Hand option. ]]

Hand's Athletics to grapple the Lich: 21

If the hand succeeds, it also squeezes the lich for 17 (force)

Quote from Mister_Whisker >>

Akkron pauses... there isn't a huge amount for him to do in this moment, but he figures he really should help the devils out a little bit. So, he points his finger and casts magic missile at the High Mage for a bit of guaranteed damage (using one charge from his Staff of Power). It ain't much, but it's honest blastin'

Magic Missile damage (rolled in game log)
3 + 5 + 4 = 12 damage.

Quote from Aaggie >>

Quote from Mister_Whisker >>

Akkron pauses... there isn't a huge amount for him to do in this moment, but he figures he really should help the devils out a little bit. So, he points his finger and casts magic missile at the High Mage for a bit of guaranteed damage (using one charge from his Staff of Power). It ain't much, but it's honest blastin'

Magic Missile damage (rolled in game log)
3 + 5 + 4 = 12 damage.

 

 You magic missiles fly true and strike, surprising the mage

Quote from Painted_Beyond >>

Hand's Athletics to grapple the Lich: 21

If the hand succeeds, it also squeezes the lich for 17 (force)

 The hand appears to have no effect 

Clarac stays where she is. If the devils want to take the heat from the lich, that is perfectly fine with her.

Still wanting to help, she casts a glittering bolt of holy energy at the undead and gets ready to put a stop to whatever magical tricks it may have up its sleeve.

OOC:

Action: Cast Guiding Bolt at first level (w/ advantage from True Strike) --> 31 to hit for 13 radiant damage. If the guiding bolt hits, the next attack roll made against the lich will be at advantage.
Reaction: Cast Counterspell at third level the next time the lich casts a spell, if it does so before Clarac's next turn.

Tyekanik: Round 1

After all of this waiting and talking, there's no way that Tyek is going to miss a fight. He moves north and to the west so that he's just behind Khessa.  The he hurls his greataxe at the Vairae for two attacks.  https://www.dndbeyond.com/classes/9-barbarian#ElementalCleaver-8396824

Movement: Move north and west to end his turn just behind Calrac.
Action: Two thrown-weapon attacks with his greataxe as his Elemental Cleaver (thunder).
  Attack 1 against Vairae: 18, Damage: 21 (magical thunder) + 21 (force) = 42 (total)
  Attack 2 against Vairae: 27, Damage: 35 (magical thunder) + 20 (force) = 55 (total)

[[OOC: While raging, Tyek's Elemental Cleaver gains the thrown property with a normal range of 20 ft.]]

Vrox: Round 1

Vrox meant what he said about letting the devils tackle the lich.  He has such a good hiding spot that he decides to remain hidden for now. He waits to see how well the devils do against the lich.

Quote from Ben_Evolent >>

Vrox would definitely Hide.  He'll be positioned just off of the stairs, hugging the north wall where that little outcropping is so that he's out-of-sight of the Vairae.

Action: Hide - Stealth 33 (advantage from Shadowfell Brand Tattoo)

Quote from Ben_Evolent >>

Tyekanik: Round 1

After all of this waiting and talking, there's no way that Tyek is going to miss a fight. He moves north and to the west so that he's just behind Khessa.  The he hurls his greataxe at the Vairae for two attacks.  https://www.dndbeyond.com/classes/9-barbarian#ElementalCleaver-8396824

Movement: Move north and west to end his turn just behind Calrac.
Action: Two thrown-weapon attacks with his greataxe as his Elemental Cleaver (thunder).
  Attack 1 against Vairae: 28, Damage: 34 (magical thunder) + 18 (force) = 52 (total)
  Attack 2 against Vairae: 33, Damage: 27 (magical thunder) + 15 (force) = 42 (total)

[[OOC: While raging, Tyek's Elemental Cleaver gains the thrown property with a normal range of 20 ft.]]

 

 Both attacks strike true with devastating effect 

Vairae grimaces in anger and lashes out at the devils still swarming him: black cages appear out of the air and fall upon the devils:

Legate 1 20

Legate 2 15

Legate 3 18

Magistrate 1  18

Magistrate 2 17

Abjudicator 6

All the devils are encased in a black energy cage that restrain them and does some type of damage to them. Vairae has a satisified smirk on his face, then he looks up at the group and his face hardens. "Well now, what to do about you all."

[[OOC: The party's turn to act again?]]

Yes, party's turn

Since her Arcane Hand failed to grab the lich, Khessa commands the hand to try to punch its dead flesh, while  she in the meantime hurls magical fire  at the undead.