REVISED TURN:

Danzu, realizing he needs a weapon, mutters a curse at the one holding the knife, hexing his strength (casting Hex, giving disadvantage on strength ability checks). 

Danzu then charges at the knife wielder, jumps at his arm, trying to take the knife from him...

I’m guessing Athletics? 15

Danzu rushes forward to Arty and attempts to grab at the blade. "Gah! Get it off!" He calls.
(Yeah, we'll go for a grapple check.)
Acrobatics: 17

The human manages to keep a hold of the blade, raising his hand in time and sidestepping.

Arty seems worried. "It's all gone wrong. T-take this, monsters!" He calls, gesturing for a spell. A BOOM of energy crackles around him from a Thunderclap
Thunderclap vs. Ba, Razznik, and Danzu: DC 12 Constitution Saving Throw, dealing 3 thunder damage on a failure.
He then tries to flee back (this provokes from all three of you)

Frank staggers back a bit. "G-guh, take this, you fiend!" He calls. He throws his dagger at Zamiel before fleeing back thirty feet.
Dagger vs. Zamiel: 14 vs. AC. Hit: 4 piercing damage.

By some sheer fluke, the dagger sticks into Zamiel. (Zamiel: 4/8 HP) Yes that means there's a dagger for Zamiel to use...

Initiative (Round 2)

18. Coy
18. Zamiel (4/8 HP)
15. Razznik
14. Ravor
10. Danzu
9. Ba

2. Arty (7 damage)
2. Frank

Zamiel pulls out the dagger and leaps at Frank, stabbing with his new dagger.

Attack: 18 Damage: 4

He also begins humming a song he remembers from his mortal days. It resonates particularly with Coy, as they feel rather bardically inspired.

(Bardic inspiration on Coy, d6)

CON save: 15

AoO roll: 12; Damage: 4

Action for turn:

Will attack whomever of the two humanoids, is the least bloodied. Swiping at them with both attacks of his claws, looking to get this over with.

Attack Rolls: 13 & 24

Damage: 4 & 3

A ball of light builds up in his body before being shot out at Arty

To hit:8

Damage:8

Con save: 4

AoO: Attack: 15 Damage: 2

Turn: Danzu grimaces and takes off after Arty trying once again to take his blade. Athletics: 9

(if arty ran his full 30ft, then I can’t catch up to him. In that case, I’d like to use the dash action... Danzu runs around bounding in front of the human, cutting off his escape. He makes a menacing snarl at him, yelling in infernal, “you weak-minded fool, running will not save you!” intimidation: 15)

Ba CON save: 11

Attack of opportunity: Attack: 11 Damage: 2

Shooting another bolt at him and running after him as well.

Attack: 15 Damage: 8

(Okay, so minor rewind)

The mage attempts to flee from the trio of devils surrounding him. While a couple are short with their swipes, one manages to strike the human deep in the lower back, causing him to collapse. (Arty: defeated, 11 damage.)

Since Arty is down, there is no need to wrestle control of his weapon away from him.

The other human is currently around 40 feet away from the group (as he was 10 feet back and then moved back another 30 feet). If you dash, you can catch up to them, otherwise ranged attacks will be your best bet.

Well, Ba is going to chase after him and try to shoot the bolt (which missed).

Razz will Dash to move in front of the man, and just ready to hit him should he move.

Danzu will run to arty, pick up his dagger and throw it at the fleeing human. 

Attack: 12 Damage: 4

(If Frank was too far away to stab, Zamiel would have thrown the dagger then)

Coy has no way to attack at range and will dash after the fleeing man.

The two daggers are hurled at the fleeing human, both managing to strike him and cause him to fall. (Frank: defeated, 8 damage.)

OUT OF COMBAT ROUNDS

You all gain 50 xp each.

Ba will search the body of Arty for aaaanything at all. 

Danzu gleefully skips up to the corpse (frank) and pulls his dagger out of the its back, wipes it on the human’s clothes, and searches the body for a sheath or any other items. 

Investigation:15

Razz is gonna look around, climbing a tree to get a high view of their surroundings.

Perception: 6

Razz, could I also get a Athletics check for your climbing a tree?

Upon inspecting Arty's body, he has upon his person a few effects:

 Upon inspecting Frank's body, he has some items, too:

Athletics: 1

Ba takes the sack with rope and shovel and also the bottles.

He opens one of the bottles and smells and tastes its contents.. would he have any idea what it is?