Sword Coast Rambling

Serak: Taking in the scene, Serak makes his way to the upper level. Seeing the bound captive, his heart feels hope for the first time that the prisoners may all still be alive. While the goblin is distracted slapping the prisoner, he then moves to the eastern boulder on the upper level and takes cover behind it, readying his crossbow and waiting for the group to make their move. 

Serak: Watching from cover as vines spring forth to entangle the goblins, the bard looks to see if the goblin on the upper level was also effected. If he's not immobilized, Serak will use his surprise action shooting him. If the goblin with the pouch is entangled, he'll target the unentangled archer instead.

Attack(Advantage-Hidden): 13

Damage: 9

Goblin Constitution Saving Throw: 5 vs Synas Spell Save DC: 13

The entangled goblin struggled helplessly against the thorny vines. The air around it grows intensely cold, but the archers struggling keeps the cold from affecting it too badly. The goblin grunts and scratches at the thorns wrapped tightly around its ankles, trying to free itself.

Up on the ledge, Serak takes aim with his crossbow at the goblin leader from behind his boulder cover. He inhales slowly. A mechanical THUNK and the crossbow bolt flies through the air. The goblin moves aside, trying to get a better view of the events unfolding below, at just the wrong moment. The bolt flies past, ricocheting of the opposing wall, falling helplessly onto the ground. 

At the chamber entrance, Zyltris analyses the chaotic scene unfolding, planning his next move carefully. 

OOC: are there goblins right now that can be engaged in meele without getting into the vines?

OOC: As far as I am concerned Beetle, they could all be engaged in melee. The vines become difficult terrain so wouldn't entrap you if you ventured in, just half your movement speed. I could be wrong but that's how I read the guidelines

Zyltris charges forward towards the nearest goblin, swinging his Morningstar with a mighty yell.

Attack: 9

Damage: 7

Beetle sees Zyltris engage a goblin and chooses the next closest to that one and brings his longsword to bear on it..

attack 14

damage 9

Zyltris and Beetle charge forward together, weapons drawn. A goblin who has avoided the thorns stands ahead of the elf. Zyltris' morningstar swings wildly through the vined chaos of the chamber. The goblin manages to dodge quickly, ducking away as the weapon comes down. Sparks fly as the blow glances off the stoned floor.

Nearby, Beetle charges down on another goblin who the vines have failed to entrap. The firelight dancing in his eyes as he swings his longsword downwards. The goblin takes the force of the blow and takes a direct hit to the shoulder. He turns to face his attacker, alerting his fellow goblins to the imminent danger.

OOC: Round one is over, proceding to round two. Goblins will attack this round.

Beetle suggested making a battle map up for the rounds so I've put this together quickly. If there's anything on it you'd like to see let me know.
(Just realised the PC Hp counts the wrong way but I'l fix that for next time)

OOC: wow that is awesome, way beyond what I was saying or pictured...lol, awesome job

OCC: Good map...

Syna will target the Goblin leader, calling forth again his magic, "moroz i snih!"

Damage:4

Goblin Constutution Saving Throw: 18 vs Synas Spell Save DC 13

Synas hands shine with a tiny bright aurora as the cold spills forth. High on the  second floor, the leader goblin surveys they scene of the surprise attack. A crossbow bolt flies past as he steps aside. As he turns to locate it’s source a slight chill comes over him. He shakes it off and continues his search.

Not far away from the fire, a scimitar wielding goblin engages with Zyltris. The clang of steel on stone echoes around as Zyltris collects himself after his miss. The goblin readies himself, swinging his scimitar madly at the elf.

Goblin attack roll: 14

The scimitar hits nothing but air as the elf dishes effortlessly.

Vines fly around wildly at the western edge of the cave as three of the goblins try to break free from its grasp. Thorns grabbing at flesh, ankles tightly wrapped.

Goblin 2 strength check: 3

Goblin 3 strength check: 0

Goblin 4 strength check: 9

Synas spell Save Dc: 13

The thick tangled vines hold firm as the trapped goblins cry out in vain.

Beetle has closed down the archer goblin causing him to struggle with his bow. Rolling away slightly, the beast notches an arrow, sending it towards the paladin.

Goblin 5 attack roll: 19, 12

Beetle deflects the attack before the arrow leaves string, catching the goblin with a shoulder charge.

On the ledge above, the goblin leader searches in vain for the source of the crossbow bolt.

Goblin leader Investigation  (Intelligence) check: 8

Seeing nothing unusual on the upper level, Serak remains hidden. The goblin leader turns his attention back to the battle below. He clashes his scimitar and shield together loudly and  shouts “Dhaan ghaar kal, mech daal ach!”

 OOC: You were too fast for me Beetle! lol

Beetle knowing goblin realizes what the leader said. "I think we pissed them off, they are crazy if they think they are going to add us to their meat pile!"

OOC: Not to look a gift horse in the mouth, but I like to play fair. After I attacked, the goblin leader knows I'm there, but the rest of the goblins still don't. Even if he can't see me, because I'm behind the bolder, he knows I'm there somewhere. He would still need to come actually actively search behind the bolder, but no Perception check would be required. 

Now, if you're saying he's either too stupid, arrogant, lazy or too distracted by the battle to actually go looking for me, that is different I supposed. Sounds like he spent his turn looking for me though, and he wouldn't need to.

If you want to change the goblin leader's action, I'm cool with it. Makes sense that he would oversee the battle I suppose, instead of joining in. Either way though, I no longer get advantage against him.

OOC: No probs Serak I admire your honesty!  I’d thought about this a bit this morning and had a bit of an issue working it out logically with the rules on attacking from cover/attacking when an enemy is fully hidden. Seeing as you’d snuck past and attacked from behind the boulder, and the attack missed I assumed the goblin wouldn’t know where it came from. Another move from Serak however and it would become obvious he was there. 

Actively searching would still have used up an action but I thought it’d be a bit unrealistic for him to find Serak immediately given he wasn’t looking in his direction at the time of the attack and had an ambush below him.

From his point of view there are only 3 attackers below him, so the roll was more of a fudge for narrative purposes, with him finding Serak after your next move. It’s fair to say your advantage is over now as he would be aware of the threat against him from somewhere. 

Zyltris centers his thoughts on crushing the goblin in front of him, swinging again. 

Attack: 8

Damage: 8

Serak: Serak quickly reloads his crossbow and sighs to himself, "Things can never be easy..." Taking steady aim, he let's loose another bolt at the goblin leader.

Attack: 18

Damage: 11

Sprinting for the ledge in hopes of distancing the creature from the captive, Serak somersaults down to the lower level. He takes position behind Beetle, waiting for the goblin leader to either come down the slope into his waiting blade, or risk the vines and thorns.

Acrobatics: 14

Another crossbow bolt whistles through the air. Seraks aim is true and decisive. It hits the goblin leader squarely in the back and escapes through his bare chest with an explosion of red liquid, barely above the head of the prisoner. Serak leaps away, somersaulting over the precipice, sliding as he lands behind Beetle, falling to one knee as he loses balance slightly. Above him the goblin leader clasps at his chest in shock. He collapses forward in a bloody crumpled mess and falls down the steep cliff face. He lies at the foot of the climb, dead

The goblin flashes a wry smile at Zyltris as the pair engage. Enraged by his leaders passing his movement becomes more slick and aggressive. Zyltris swings his Morningstar sideways hoping to catch the goblin off guard, but slices through the smokey cave air harmlessly. The goblin roars a weezing evil threat in the goblin tongue as he dodges the blow.

Beetle, aware of everything going on around him needs to finish this goblin so he can help out with the others.  He quickly asks Tyr to guide his blade once more then swings his longsword again at G5...

Attack: 19  if hits damage: 8

 If the goblin dies, Beetle then uses his movement to avoid the vines (even if he doesn't should be able to get to them with 15 ft movement looks like it is only about that on the map) and move around the fire to engage G4&G2 next, especially the archer G4

 As Beetle positions himself to occupy the other he says..."NICE SHOT Serak...I think the leader is down...but I only give you a 7/10 on the flip, gonna have to work on that"