Xanrym, still in the strange priest's quarters (room 17) can barely see the crazed man moving to attack.  He says, "Can you flank him, Liarin?", hoping that it'll clear the way for him and Theldrin to get into the room. 

Xanrym casts vicious mockery on the priest, hoping to protect his companions.  He says, "The toothless dog has no bite!  So, too, with you!"

Movement: If Avery or Liarin manage to move into the room, Xanrym moves forward through the ruined door and then to the right, along the wall in room 18.
Action: Cast spell Vicious Mockery, WIS 13 save or target takes damage (4 psychic) and has disadvantage on the next attack roll it makes before the end of its next turn.
Free Action: Talking

The Firebolt hits the priest in the chest but he moves on, chuckling. 

Wis Save: 10

The priest shakes his head at the magical insult, and continues towards Avery and Liarin. Slightly put off.

Avery is up, the priest is still coming at you.

Avery attacks: 14; Damage: 11

That's a miss but because if Viscous Mockery you get advantage, i'll roll that for you now: 23

Avery's sword bites into the priest's armour, he gives out a bloodcurdling shriek, "You would attack her property? The unworthy heretic Abramo! You will pay for this defilement." He swings his mace at Avery:

Attack: 7 Damage: 4

He misses with his mace, and will immediately cast Shield of Faith . A visage of a snake envelopes Abramo, protecting him from hits. (+2 AC)

You all are up.

Liarin moves to put her bulk between the lunatic and the prisoner, then attempts to bite and rend him with her claws.

Bite Attack: 22 Damage: 5
Claw Attack: 11 Damage: 14

Xanrym says, "Did he say Abramo?!  The former high priest?  We need to take him alive!"  Moving through the ruined door, he sees the cage.  Xanrym stows his crossbow and starts moving along the west wall of the room toward the prisoner's cage, trying to make sure that Avery or Liarin is between him and the mad priest.  As he goes, he again tries to rattle the priest with vicious mockery, saying, "Neither property nor a heretic, you!  Abramo knows that you're just stark, raving mad!"  He also tries to inspire Avery by saying, "Avery, this madman must have corrupted Sir Grover.  Now's your chance to mete out justice!"

By the light of his lantern, does Xanrym see any other cultists or goblins or creatures hiding in the room?  (Perception 9)

Movement: Now that Liarin has moved into the room more, move 30' through the ruined door and then south along the west wall of the room.
Action: Cast spell Vicious Mockery on the priest, WIS 13 save or target takes damage (4 psychic) and has disadvantage on the next attack roll it makes before the end of its next turn.
Bonus Action: Grant bardic inspiration to Avery.
Free Action: Talking

(OOC: It seems like this is the last room on the second floor.  It might be a good time for Avery to use action surge.  Since a 14 was a miss even before Abramo put up shield of faith, Xanrym gave Avery bardic inspiration to help with his next attack.  He wants to finish this fight fast before we find out what else the priest can do.)

"Abramo..." Theldrin mutters under his breath as he stares at the priest.  He thinks back to the battle at the Inn, not wanting to accidentally kill him.  He reluctantly holds off on attacking for now.  hoping Avery and Liarin can subdue him.

Inspired to do justice and seek revenge of the corruption against Sir Grover, Avery goes into the attack: Attack: 14 Damage: 14

(OOC: @Aaggie, note that bardic inspiration, in this case, lets you roll a 1d6 and add it to your attack roll.  It's different from inspiration, which lets you roll with advantage.)

Liarin's bite attack sinks into Abramo's neck, but her claws swipe against his armour ineffectively. 

Xanrym sees noone but Abramo and his prisoner, Abramo WIS Save: 13

Theldrin, you see that Abramo is still looking pretty good despite suffering attacks from the others. He could probably take a firebolt or two before becoming injured. Especially seeing as how Avery just missed. We'll say that he has used his bardic inspiration for that last attack.

Abramo looks at you all, "He hehe. He may need some reinforcements here from the master herself." He clasps his hands together and casts Spirit Guardians . Fluorescent green snakes fly out of Abramo and hover around him, biting anyone who's standing too close. Anyone standing next to Abramo must make a DC 13 WIS Save at the start of their turns or take 3d8 Necrotic Damage (half on a save), and will continue to take it one each turn until the spell ends or they move out of range of the snakes. Also their movement speed is halved, so they can only move one square at a time if they start their turn next to Abramo.

You all are up, Abramo is standing with his hands clasped summoning evil spirit snakes to bite y'all. Avery and Liarin will have to make DC 13 WIS saves at the start of their turns if they're next to Abramo.

Abramo shakes off the insult this time, "He grows used to your tricks, BARD!" He laughs, but not in the way you wanted.

Quote from Ben_Evolent >>

(OOC: @Aaggie, note that bardic inspiration, in this case, lets you roll a 1d6 and add it to your attack roll.  It's different from inspiration, which lets you roll with advantage.)

 3

Attack now 17

I ruled before that you had used your bardic inspiration for the advantage, rather than adding a d6.

By the way though, when the snakes attack, you see the shield of faith drop. Both spells require concentration.

[[Wis Save: 21 on sheet]]

Liarin continues attacking Abramo, but tries to keep from killing him as requested.

Bite Attack: 22 Damage: 7
Claw Attack: 20 Damage: 10

Quote from drumdigby >>

you see that Abramo is still looking pretty good despite suffering attacks from the others.  

Xanrym moves across the chamber to position himself near the cage, using the crude statue on the southwest as cover.  Seeing that Abramo has powers beyond his simple attacks and that the priest still looks relatively uninjured, Xanrym sets his lantern down, gets out his crossbow, and fires on the priest.  As he goes to draw another crossbow bolt, he tells the prisoner, "Don't worry: we're going to set your free.  I'm Xanrym.  What's your name?"

Movement: Up to 30' to move south and then east, ending up near the cage, south of the southernmost statue.
Action: Attack Abramo, Crossbow, Light (80/320): 13, Damage: 6
Free Action: Item interaction: equip crossbow.  Talking.

Noting that Abramo seems like he can handle some more injury and not liking the look of the spirit snakes attacking Avery and Liarin, Theldrin decides to continue the attack.  He carefully aims another Fire Bolt at the priest's chest.

Attack: 15 Damage: 3