The red wizard takes the blow. Both of them are quite injured, but they have still the strength to cast one spell each. The air fills with magic...

Irommek --> WIS saving throw

Gertrude and Kurma --> WIS saving throw (Gertrude with advantage)

Inete, Dragonbait and Musharib WIS saves: 16, 9, 20

Round 2
Gertrude (38/57, Rage 9) - Thug 1 (22) - Thug 2 (26) - Thug 3 (36) - Thug 4 - Thug 5 - Thug 6 - Thug 7 (6) - Musharib (67/67+3, pass without trace) - Artus (82/82+3) - Dragonbait (120/120+3, charmed by Thazma) - Inete (40/40+3) - Oniss (32/32+3) - Irommek (49/49+3) - Yamoch  (61, 1(1) 4(1)) - Thazma (43, guiding bolt, 1(1) 5(1)) - Felix (38/38+3) - Kurma (32/32+3, charmed by Thazma) - Brunella (60/60+3, Rage 10)

Wisdom saving throw: 13

WIS saves: 13

Quote from RonanKP >>

WIS saves: 13

 Thazma: " My dear friend, I wish only to talk. Perhaps we can help each other. "
Persuasion 17

Quote from filcat >>

 Thazma: " My dear friend, I wish only to talk. Perhaps we can help each other. "
Persuasion 17

 
Insight: 27

Kurma stoods motionless for a few second. Something tells him the mage may not be dangerous, but something is odd. It is hard to tell.
Scanning the rest of the group, Kurma sees aggression, anger, evil...

"I am not sure about you, mage, but these ones, I know for sure, are up to no good. This is not help"

Kurma then runs at proximity to the mage and focuses on his amulet, muttering prayers. In a bright flash, agelic forms appear around the tortle, flying in a chaotic pattern and delivering burst of light every time they touch an enemy. In a strange manners, these small angels manage to avoid Kurma friends and the mage Thazma.
Casting Spirit Guardians WIS 15 at the start of their turn on all thugs and the other mage... if fail : speed half and 3d8 radiant damage

EDIT: the "potential problem" is because i rolled the 3d8 but then remove them as I think each creature need to roll separately and on each turn.. So I cannot roll just once

Felix will arch his bow and loose another arrow on the one that spoke. (Thazma)

Hit: 23

Damage: [roll]1d6+3[roll]

Sneak Attack: 8

Damage: 5

Round 2
Gertrude (38/57, Rage 9) - Thug 1 (22) - Thug 2 (26) - Thug 3 (36) - Thug 4 - Thug 5 - Thug 6 - Thug 7 (6) - Musharib (67/67+3, pass without trace) - Artus (82/82+3) - Dragonbait (120/120+3, charmed by Thazma) - Inete (40/40+3) - Oniss (32/32+3) - Irommek (49/49+3) - Yamoch  (61, 1(1) 4(1)) - Thazma (65, guiding bolt, 1(1) 5(1)) - Felix (38/38+3) - Kurma (32/32+3, spirit guardians, charmed by Thazma) - Brunella (60/60+3, Rage 9)

With the speed of an eagle in flight, Brunella runs to the red wizard, the same she targeted with her javelins, and cleaves mightily at the robed figure. (Brun will attack twice, but if the first attack kills the target, she will move to the other red wizard and use the second attack on him (Rolling advantage due to flanking). Her second cut is especially devastating, as she stabs the heavy stone handled sword through the stomach of the wizard! She screams like an eagle triumphantly grabbing its prey, a shrill cry that pierces the air of the lost city.

Thazma has the change to give a look to her internal organs before dying.

Round 3
Gertrude (38/57, Rage 9) - Thug 1 (22) - Thug 2 (26) - Thug 3 (36) - Thug 4 - Thug 5 - Thug 6 - Thug 7 (6) - Musharib (67/67+3, pass without trace) - Artus (82/82+3) - Dragonbait (120/120+3) - Inete (40/40+3) - Oniss (32/32+3) - Irommek (49/49+3) - Yamoch  (61, 1(1) 4(1)) - Thazma (65, 1(1) 5(1)) - Felix (38/38+3) - Kurma (32/32+3, spirit guardians) - Brunella (60/60+3, Rage 9)

 Brunella's second attack cuts through the wizard like a hot knife through butter. The sword eviscerates her, and organs fall to the ground in a wet pile. The wizard looks down at the hole where her entrails used to be, and has the time to make a surprised face. "Oh..." she says, before the light leaves her eyes. 
Brunella uses her massive strength to pull the sword back and upwards, bringing the great blade up through the neck and skull. The blade cuts the wizard's face in two, going up from the neck to the tip of the skull, and the two sides of her face fall to each side on the ground like a peeled banana. Small pieces of brains and blood flick the face of the other wizard, who looks at Brunella's matching grim gaze, staring straight back. The wizard feels his bowels turning to jelly.

WIS Save 21

OOC By the way, Kurma is technically still charmed by Thazma, and Brunella just killed her...

"Nooo, BRunella ! What have you done ! She was friendly, she was the only one of the lot that was friendly. Inete heal her, do something !"

After one of the mages falls, Gertrude turns her attention to the remaining one [Yamoch - assuming advantage because of flanking with Kurma (?), if not, please only consider first roll].

She takes a wide arc and swings her greataxe at him:

to hit 27 for damage 16 if advantage then additional damage of 9 (because of crit)

Then she swings again:

to hit 25 for damage 18

[If Yamoch falls from the first hit, then I'll hit thug 1 - for advantage because I am flanking him with Dragonbait]

Then Gertrude again feels her rage rising for the protection of her companions. (+3 tHP to whoever is around her)

Yamoch the red wizard had lungs once. Not anymore.

One more thug falls unconscious. The rest realise it is better to flee into the unknown in the city. Musharib and Artus leave them be, while Inete tries to calm down Drabonbait which is upset with the death of the female wizard as well.

Round 3
Gertrude (38/57+3, Rage 9) - Thug 1 (22) - Thug 2 (26) - Thug 3 (36) - Thug 4 (6) - Thug 5 - Thug 6 - Thug 7 (6) - Musharib (67/67+3, pass without trace) - Artus (82/82+3) - Dragonbait (120/120+3) - Inete (40/40+3) - Oniss (32/32+3) - Irommek (49/49+3) - Yamoch  (61, 1(1) 4(1)) - Thazma (65, 1(1) 5(1)) - Felix (38/38+3) - Kurma (32/32+3, spirit guardians) - Brunella (60/60+3, Rage 9)

Thugs WIS saves for spirit guardians: 19, 13, 17, 15
Radiant Damage 16

Seeing the crazed look in Kurma's eyes, Irommek curses uder his breath. 

"Damn red wizards.  This is their handiwork."

Irommek tries to console Kurma in only the way that a dwarf fighter can.

"Um, it's OK Kurma.  Just their time to go.  No biggie.  I hear that red wizards consider it an honor to leave this plane by having their skulls cleaved in two..."

OOC: Persuasion check (19)

Quote from Spock >>

Seeing the crazed look in Kurma's eyes, Irommek curses uder his breath. 

"Damn red wizards.  This is their handiwork."

Irommek tries to console Kurma in only the way that a dwarf fighter can.

"Um, it's OK Kurma.  Just their time to go.  No biggie.  I hear that red wizards consider it an honor to leave this plane by having their skulls cleaved in two..."

OOC: Persuasion check (19)

 Irommek's words sound very true to Kurma. The old dwarf is really the voice of experience and wisdom.

Kurma stop trying to put back the intestins of the mage back in her belly. "Maybe you are right, Irommek. It is a sad way to die though These Thayans, they have weird customs."
After a long silence, Kurma turns to the dwarf. "Maybe we should at least bury her... We cannot let her here as meat for the animals... What do you think?"