I'll move back so that I'm next to stool and I'll cast a fireball 20 feet east of the goblin boss' location.  damage= 33.  I'll then move back further so that I am next to Leon and hovering as high as possible.  End turn.

    Morgana's inner magic builds within her and she concentrates on a point that she knows will only damage the two goblins in range of the explosion...her Fireball coalesces in front of her hands and she wills it with immense force at the location in mind.  It howls as it tears through the air and crashes with a fiery explosion - completely incinerating the Goblin Boss and one of the smaller Goblins, and reducing them both to a smoldering pile of bones.

    The two remaining Goblins both stand completely still, mouth agape as they feebly try to reconcile what just happened to their boss.  Looking at each other only momentarily, they both drop their scimitars, throw up hands, and run as fast as they can in the other direction!  They manage to get around the tunnel wall that leads away from the larger space that you're currently at the entrance to and are currently not visible from anyone's vantage point.

Leon turns to Stool.

”Keep up with Miss Morgana. I am going after these fools”

I'll follow on Leon's heels and have stool switch to friendship spores while we move.  

Perception check 6 plus guidance 1

Gremryl with slightly singed eyebrows and beard (dammit)

"Morgana, now THATS how you exterminate goblin vermin!! Barharharharhar!!! I'll try to catch up to them!!" 

I'll move my maximum distance then cast Misty Step to get to the inside if the tunnel. Weapons ready and perception check 15

Leon will activate his boots as a bonus action. Leon will move 60ft foward and dash (adding up to another 60ft of movement) to close the gap on the closest goblin, get in front of him and  block his path.

    Chasing after the goblins, Gremryl moves first and is able to make it into a carved out section of the tunnel that has a fast flowing river flowing through it, creating a wide break in the floor about 35 feet long.  No goblins in sight...until suddenly, whizzing through the air comes an arrow that lands deep into Gremryl's left shoulder!  From the other side of the river, he sees one of the goblins!  It then darts back into the shadows and Gremryl has lost sight of it...Then another arrow comes whizzing towards the Paladin, but this time, it's deflected by Gremryl's shield, with the quick reflexes borne from decades of combat.  That Goblin looks to curse from the other side of the river, then also disappears into the shadows.

    Leon dashes after Gremryl to help chase down the goblins.  As he approaches Gremryl, in his haste, he neglects to notice a spring-loaded trap in the cavern floor!  When he steps onto the trap, a loud *CLICK* is heard and a split-second pause occurs, as Leon instantly looks up at Gremryl with an "Ooops..." look on his face.

Leon and Gremryl - Roll a Dexterity check! (Don't forget to include the Bless buff)

Dex save

Dex save 912 bless buff 2

Dont like the sound of that Lad...

6 plus bless 2

    The hissing noise from the walls alerts Gremryl and Leon to a gas being released into the chamber. It’s a thick, dark green cloud that permeates the air around them.

    Gremryl quickly covers his mouth and noise before the gas reaches his airways, however Leon isn’t as fortunate and is knocked unconscious from the poison.

    Morgana, unaware of the trap being sprung, is next to take action!!

Well, I know what I would like to do.  But from a RP stand point...

Morgana continues to charge towards where she saw Grem and Leon round the corner.

Morgana - Roll a Perception check!

perception= 12

To stool:  "Hold it!  Don't move!  Wait for instructions.

Morgana stops short.  Psychically to Leon and Grem:  "Why does it smell like a trolls dead **** in here?  Talk to me, boys!  Anything going on that I need to know about?!"

Gremryl makes the universal motions for "Noxious gas clouds  could  kill you" sign