Derro 1 DEX Save: 4

Derro 2 DEX Save: 13

Derro 3 DEX Save: 6

Derro 4 DEX Save: 21

Derro 5 DEX Save: 4

Derro 6 DEX Save: 22

The crows fly into the townhouse, tearing through the derro in the first two room, killing 1, 2, 3, and 5.

The rest of you are all still up.

Coriana runs across the first room and attacks the remaining derro. (Derro3)

Attack: 26 Damage: 9 Slashing
Attack: 17 Damage: 10 Slashing

She summons her remaining tentacle by Derro 6 and lashes at him.
Attack: 15 Damage: 9 Cold

And both those derro go down.

Avery, Theldrin, Xanrum, and Khessa still up. Your friends have cleared out the front part of the townhouse. You could back them up, try going through the back, or maybe a window. 

Theldrin aims a Fire Bolt at a Derro, through one of the townhouse windows.

Attack: 8 Damage: 13

Avery attacks the closest guard, clearing the door and moving to the side if possible: attack Attack: 11 Damage: 14; Attack: 9 Damage: 14