"I wonder what kind of danger we've gotten ourselves into this time?" Geoffrey asks 'no one in particular' as he stares out the window.

(Prior to the whisper, he would have been listening to the music. How good is it, compared to them?)

Kagenthur notices the recognition of the invisible speaker in Geoffrey's voice, and adds, "I don't know, but if somebody does, I've half a mind to track them down and get some real answers." quietly while looking into his drink. 

He then looks over to the female guard again and asks much louder, "So, is it any good? The wine?" trying to start a subtle distraction so anyone with an actual plan can carry it out. 

Boisseau stares at his cup that he still hadn't taken a drink of. "Well better safe then sorry, I can cure this wine of any foul doing, there is a little trick I picked up to help deal with... questionable dining establishments." Boisseau had traveled with a paranoid wizard who always casted some clean food spell on everything they ate. Boisseau never learned the spell but did think it was a distraction enough with Kagenthur additional attention assistance. He casts See Invisibility and turns to see if he can make sense of what he will see.

He will Message with the newcomer and rely messaged to the others in a similar fashion.

Geoffrey sets his attention on the music coming from the other room. He discerns only two instruments: a lute and an alto voice. The current song seems to be a thoughtful ballad, well-played and sung, but it's hard to know for certain with the sound being dampened by the walls. 

The female fiend turns her attention to Kagenthur and non-chalantly responds, "Rahmzur selects only the best. That goes for the wine as well as his musical guests. It's an honor of sorts, although I suppose it may not seem so to you at this moment."

She then sits in a nearby chair, further indicating her absence of concern about keeping watch. 

 - - - 

Meanwhile, Boisseau and Zolya hear the whispered voice a second time. "Prepare yourselves as I create a distraction."

The mysterious speaker offers no further explanation, and a few seconds later the "distraction" unfolds. One of the flagons of wine rises from the table, streaks through the air, and smashes into the wall in the northeast corner of the room (to the right of guard 2). Moments later, the empty chair next to the female guard is upended. The guards' attention is fully focused on the inexplicable commotion in that area of the room (upper right corner), leaving all four of you with a chance to add to the guards' surprise should you choose to do so. 

You hear a short, gleeful laugh from the one who just set this chain of events into motion. 

EDIT: Boisseau, however, is able to see a bit more of the story. A female fiend--a cambion, in fact--who has a very similar appearance to Rahmzur du Mar, is the one in the room causing the distraction. She is standing on the low table in the center of the room. 

The guards are surprised; so, each of you may act in any order (no need for initiative rolls). See map for locations of characters and guards.

Boisseau goes one by one sending the message: Female version of host is behind distraction

Interesting. Our host has changed form to another gender? Is this a trick? Zolya thinks to himself. He whispers to the rest of the party "What do we do? We could kill the guards and escape, but we have nowhere to go" He seems to have no quals about killing the fiends, though the rest of the party would remember that when it comes to mortals his morals are a lot more friendly. Unholy abominations on the other hand, deserve to be smited. 

With a whispered encouragement, Zolya pats Kagenthur on the shoulder, giving him a Bardic Inspiration, as a small glowing angelic orb now floats around Kagenthur. He gets to add a 1d6 to his next attack, save, or ability check. When you use the bardic inspiration die, an additional effect happens based on which type of check you use it for:

With a nod, Kagenthur acknowledges Zolya's help and Boisseau's message. 

"Ready when you are." He says to the group and our invisible ally. 

"Guess it starts with me then ehy? Alright, let's crack some skulls!" 

With a roar, Kagenthur charges forward at the nearest adversary and starts swinging. 

Action Attack 1:

Attack: 21 Damage: 12

Action Attack 2: 

Attack: 12 Damage: 13

Bonus Action Attack:

Attack: 17 Damage: 7

OOC: Does Kag's attacks hit?

Kag rushes forward, half-leaping over the short table between himself and the female fiend. Three times his blows land, badly wounding her; she lets out an angry snarl. 

The room now erupts into full chaos as the first real blows have been struck. 

(Zolya may act in this surprise round, after which I'll roll initiative for everyone)

With a shout, Zolya runs forward, strumming his lyre, and looks at one of the Burly Fiend Guards. He stops, and yells "In the name of the Holy Lord, I command thee to grovel!"

Zolya casts command, using the Grovel effect. the Fiend Guard must succeed on a DC 15 Wisdom Save or:

The sound of Zolya's lyre fills the room, and immediately thereafter one of the guards (#3) falls to the lounge floor, unable to resist the enchantment directed at him. Boisseau, still able to see all that is invisible, watches the hidden female cambion walk toward the north wall where she seemingly will wait and watch the battle play out. 
__________________________________________________________________________________

Round 1 of combat has begun. Boisseau, Kagenthur, and Geoffrey may act in any order. The female fiend, who is still seated and denoted in orange, will follow. Zolya will then act. Refer to the map above (post #24) for locations of foes. Fiend 3 is prone, and the female fiend is moderately wounded. 

Boisseau will cast Eldritch Blast and send both bolts towards the female guard.

Attack 1: 19 Damage: 9

Attack 2 : 12 Damage: 6

(Well that could have gone better...)

Boisseau moves around the others and will put himself between the wall and Kagenthur next to the chair in that spot.

Kagenthur will keep swinging till the guard he's focused on his knocked unconscious.

Attack 1
17
8

Attack 2
24
8

Bonus Attack
10
6

Quote from Man_of_Dust >>

The sound of Zolya's lyre fills the room, and immediately thereafter one of the guards (#3) falls to the lounge floor, unable to resist the enchantment directed at him. Boisseau, still able to see all that is invisible, watches the hidden female cambion walk toward the north wall where she seemingly will wait and watch the battle play out. 
__________________________________________________________________________________

Round 1 of combat has begun. Boisseau, Kagenthur, and Geoffrey may act in any order. The female fiend, who is still seated and denoted in orange, will follow. Zolya will then act. Refer to the map above (post #24) for locations of foes. Fiend 3 is prone, and the female fiend is moderately wounded. 

 OOC: to be clear, the guard does not drop prone until their turn, in which they spend the whole if it dropping prone, so right now, they aren't prone, but when it coems to their turn, they will not get one and instead just drop prone. From the text of command:

The target must succeed on a Wisdom saving throw or follow the command on its next turn...Grovel. The target falls prone and then ends its turn.

(Per the clarification above, guard 3 is not yet prone. Thanks, Raccoon_Master)

Boisseau's eldritch blasts strike the female fiend twice, but wound her only slightly. Moments later, Kagenthur's hammer delivers a pair of blows to the same fiend, who shows clear indications of being badly wounded. 

Geoffrey's action is next. The female fiend will follow; after which, Zolya will act. 

5Geoffrey will bring out his rapier and dagger and attack the nearest one, other than #3. 

Attack: 19 Damage: 9

Bonus Action - Dagger Attack: 16 Damage: 3

if either hit then add sneak attack

Geoffrey moves toward the female fiend and uses his dagger to strike the fatal blow. The she-devil lets out a low screech as she slumps lifeless in the chair. 

Zolya may act; the three brutish guards will then follow. 

Zolya barks imperiously at the Fiend Guard which he cast command on "NOW!"

With a pluck of their lyre, Zolya sends forth a bolt of divine energy, the divine fire searing the mind of a different Fiend Guard, making them clumsy. He casts guiding bolt

Guiding Bolt Attack: 14 to hit, 18 Radiant damage, and the next attack made against that guard has advantage