The other kobold attacking Crush is struck dead by Aria's arrow. 

Sen is up.

Sen looks for any nearby kobold engaged in aggressive action against an innocent bar patron, and fires a Ray of Frost at it: 

 Attack: 11 Damage: 4. 

He also makes sure to stay as far away from the actual battle as he can.

Sen sends a ray of frost at a kobold, but it misses.

Crush is up. 

Aria yells out "FALL BACK ON ME!"  

Crush will snarl before letting out a loud and hardy laugh. "Puny bugs get smashed!" The orc would shout as he swings his hand axes violently towards the nearby kobolds. 

Attack: 21 Damage: 6
Attack: 20 Damage: 7

(Action surge)

Attack: 20 Damage: 6

Plus bardic inspiration to an attack roll 5

Adding the inspiration where in the most advantageous spot, Crush wipes out three kobolds, laughing all the while. Two more jump in to replace their fallen brethren, attacking Crush with their daggers:

Attack: 17 Damage: 5
Attack: 12 Damage: 3

A third takes a shot at Veryes with its sling:

Attack: 17 Damage: 4

Two more emerge from the portal, survey the scene, and begin shouting something back down into the hole. The others continue attacking other patrons and/or generally causing chaos in the tavern.

On his turn, Shadrach takes a swing with his greatsword at the nearest kobold:

Attack: 24 Damage: 11

And then moves towards the portal himself, intent on stopping whatever it is the two kobolds who just appeared are attempting to do. 

Usul is up.

Usul will again try to duck behind cover in an attempt to get a surprise shot off at one of the kobolds. stealth 15 Finding it easy to hide in the chaos he pops out and shoots at another one, focusing on those surrounding his large tusk toothed friend.

Attack: 25 Damage: 19

(Can I position myself by the portal to catch the 2 kobolds there in a 15' cube and not Shad?)

You can. Describe what Veryes is going to do.

Veryes is going to position herself next to the portal to get as many kobolds in her AOE as possible and try to send them blasting away from the portal into the wall, or anything else nearby that would mess them up. 

She casts thunderwave Con 13 save for half and not being pushed 10' away from me.

Damage: 8

The two kobolds who were shouting down the portal are blasted into the opposite wall, hitting with a wet thud and then falling down the portal.

Aria is up.

(( Whats the scene like at this point? ))

It's chaos in the Yawning Portal. The party plus Shadrach are doing their part to beat back the kobolds; there are quite a few of them dead on the ground. Though the party has been successful thus far, the kobolds have caused quite a bit of damage -- smashed glasses and plates and furniture, throwing all kinds of food around, smashed a few kegs, and done not an insignificant amount of damage to the patrons. There were two kobolds who had come out of the portal and were shouting something back down behind them, but they got blasted back down the hole. That caused some of the remaining kobolds to freeze in a panic, like part of their plan might have just been derailed. 

After surveying the carnage that has taken place in the Yawning Portal, Aria dashes to a chair, hops up onto a table right by the mouth of the portal... looking down she fires one of her tracer arrows into it to see if that illuminates anything.

ATTACK ROLL IN CASE: 20

At the bottom of the pit, Aria sees a group of kobolds surrounding some kind of barrel, the bodies of the two Veryes just killed laying on top of some sort of barrel. The kobolds are yelling at each other when Aria's arrow lights up the space and they shriek and run back. The arrow hits the barrel squarely and everything goes quiet for a second. Though the magical flare on the tracer arrow doesn't have any incendiary properties, the torch one of the kobolds dropped when it ran away does.

If this was a movie, you'd see the torch roll on the ground, and a spark leap to a thin trail of liquid left by the barrel as they moved it into position. The liquid would ignite and the fire would race to the barrel. The kobolds try to scramble - some run into the fire and start screaming, others bolt in the opposite direction. One is pumping his arms like a track athlete running in slow motion. 

The fire trail hits the barrel.

There is an explosion. In the tavern, the floorboards expand and contract and there is a belch of fire and smoke from the portal itself, which Aria is leaning over and Veryes is next to. I need a dex save from both, with disadvantage for Aria since she is leaning directly over the blast. (Either of you can substitute acrobatics for straight dex if you want to add a flourish to it). 

ACROBATICS: 7

Veryes Acrobatics: 22

Quote from BTI_Brian >>

Veryes Acrobatics: 16

 (( Glad that will work out for someone lol ))

Veryes tumbles out of the way, diving behind an overturned table to protect herself from the blast 

Aria takes 11 damage.

Sen is up.

Edit: Aria flies across the room in slow motion from the blast, scorched from the blast. She hits the floor hard. She's unconscious - the blast almost killed her.