(Sorry, accident turned into something bigger so responses will be sporadic for a while.)

Con Save - 20

Cultist - The cultist reappears, at the center of the group behind. But their appearance of a cultist has faded, revealing a woman in simple clothing holding a dagger. She goes for Gorin before disappearing once more.

Attack: 9 Damage: 9 (x2 damage for Vulnerability)

Vaaz - He slashes wildly once more between Arkon and Zim and glares at Mara

Attack: 8 Damage: 8 at Arkon
Attack: 17 Damage: 11 at Zim

WIS Save for Mara, DC 14, on fail - stunned until end of your next turn.

WIS Save for Mara (DC 14): 9 (failure)

Vaaz's stab bounces off of Arkon's armor as the goliath heaves his own heavy blade in retaliation.

Action: greatsword to hit with advantage from Mara's help 20, damage 10

The young red-haired patriar sighs and unleashes cone of hellish flames to incinerate the annoying bhaalist. "Better take care of this one first." She says grimly to Sarris and Gorin.
(Cast Burning Hands, Fire: 16 Dex save 14 for half)

Meanwhile the tiny invisible imp flutters back to his mistress and does his best to keep track of the invisible female bhaalist for her.
(Perception: 9 )

Quote from Oberon99 >>

The young red-haired patriar sighs and unleashes cone of hellish flames to incinerate the annoying bhaalist. "Better take care of this one first." She says grimly to Sarris and Gorin.
(Cast Burning Hands, Fire: 16 Dex save 14 for half)

Meanwhile the tiny invisible imp flutters back to his mistress and does his best to keep track of the invisible female bhaalist for her.
(Perception: 9 )

 

 ? is where the cultist was last seen.

(Sarris is still up to act)

Sarris continues with his pop, shoot, return, reset.  Sooner or later, one of his arrows is going to hit something to halt Vaaz in his tracks.

Longbow - To Hit: 26   Dmg: 11 piercing. + 3 force (Hunter's Mark) == 14 pts

The tiny invisible imp again distract Vaaz before taking cover.

Realizing she doesn't know where the pesky bhaalist went, the young red-haired patriar again peeks out and unleashes a hellishly red beam of eldritch crackling force towards the hopefully distracted Vaaz before dodging back into cover.

Eldritch Blast: 20 Another attack roll if helped by Mal's distraction: 19 Force: 7 Necrotic: 2

Quote from Kol_Drake >>

Sarris continues with his pop, shoot, return, reset.  Sooner or later, one of his arrows is going to hit something to halt Vaaz in his tracks.

Longbow - To Hit: 26   Dmg: 11 piercing. + 3 force (Hunter's Mark) == 14 pts

 Sarris's arrow pierces Vaaz's chest once more and again the man just takes the shot.

Arkon, how do you want to kill Vaaz?

Arkon hears Mara's advice to aim for Vaaz's knee, but takes it a step further by bisecting him at the waist. He is slightly surprised when the skull-headed cultist falls dead.

Ekko, Mara's bat, flies (dash) to the commotion in the back room after Vaaz is defeated. It has Blindsight of 30ft and can circle fluttering around the spot where the cultist is invisible and then hides behind the nearest of her allies. 

With Ekko's help, the invisible's location can be determined. (Still invisible so attack rolls against it will still be at disadvantage.)

(Val, Gorin, and Bot Zim are up. Will bot Zim with a dash to go there.)

"You should have fled while you had the chance." The young red-haired patriar says grimly as she is made aware of the cultist still remaining, swiftly stepping closer to unleash a cone of hellish flames to incinerate the annoying bhaalist. She then retreats towards the west and takes cover.

(Cast Burning Hands, Fire: 12 Dex save 14 for half, will end movement in i2)

Meanwhile the tiny invisible imp flutters back to his mistress and does his best to keep track of the invisible female bhaalist for her.
(Perception: 10 )

Dex Save: 16

Gorin casts catapult on a stone or something weighing between 1 and 5 pounds throwing it to where the cultist should be

DC14 DEX save or take 18dmg