Clambering up and over the fallen timber, Thurodim slashes upwards at Peryton 1 as it tries to gain height. The first strike opens a gaping wound in its belly that gushes blood down onto Thurodim, while the second strike finishes the job - the creature's damaged underside opens and its guts spill out at Thurodim's feet, soon followed by the peryton itself, crashing down.

Remaining are the peryton opposite the stairs, still on the ground, and one anticlockwise from the stairs, 10ft in the air. Succeeding on the Acrobatics check from the stairs will close the distance, but only Ghurr and Thurodim have the height/reach to melee attack it.

There is only enough space immediately at the stairs exit for one person, so for those coming up the options are moving onto the timbers or allowing those behind to push past you.

Faera runs up after Thurodim, and as he obliterates the flying beast in front of him, she about stands there in shock.  Knowing there are more, she turns South out of the stairs and moves directly south of the stairwell to get out of the way of others.  Focusing on the one in the air, she fires off a firebolt.

Attack: 18 Damage: 5

Ghurr comes out behind Faera, takes in the situation quickly and heads south across the beams, dancing along them as quickly as he can.

Acrobatics: 5  

Ghurr manages to get his balance quickly and runs along the beams with barely a slip, as soon as he manages to get within range of the preyton, he slashes upwards at the edge of his reach with his glaive, twirling it quickly to strike the creature again before it can rise higher into the air, and then spins it again to catch the bird-deer with the butt of the handle.

Action: Attack 1 - Attack: 27 Damage: 7  

Attack 2 - Attack: 10 Damage: 7  

Bonus Action: Polearm Master Bonus Attack: Attack: 21 Damage: 7  

Bugbear Surprise Attack on creature that hasn't taken a turn yet in combat - if one of attacks above hits, extra 6  damage.

Divine Smite - On first attack that hits, will add a Divine Smite - 3  radiant damage

Mala will head to the SW as she arrives at the top of the stairs, her longbow in hand. She will focus on the peryton that is in the air as well. First she casts Hunter's Mark on the creature and then quickly fires two arrows. 
(Longbow Attack: 16 Damage: 8 + 4)
(Longbow Attack: 9 Damage: 11 + 4)

(Guys seriously, these rolls! Time for a Tarrasque?)

Ghurr seems hardly to touch the loose beams, his sense of balance belying his size. As he reaches the peryton a blossom of fire erupts from it, Faera's Fire Bolt. Distracted by the flame, the creature is easy prey for the hurricane of steel and wood, and it is quickly brought down. It lies dead on the wood, a wing nearly sliced clean through, bones broken under the weight of Ghurr's blows.

Mala, do you want to redirect your arrows to the one still on the ground opposite the stairs?

(Yes please, if that is the only one still standing!) 

(Yep! You lot are damage machines apparently!)

Emerging from the stairs, Mala sees one peryton already dead at Thurodim's feet as he roars his fury, and see Faera and Ghurr take another down together. Facing you across the rooftop is another, wings outstretched threateningly, bellowing almost as loudly as Thurodim, but seemingly reluctant to take to the air. 

Finding your Mark, you release your arrows in quick succession, thwip thwip, and they embed deeply in the peryton's exposed chest, the fletching visible as two coloured dots among the white feathers, now slowly turning a deep red. It stumbles and collapses forward in its nest. As it struggles to raise its head above the fallen timbers it continues to roar and grunt, but weakly. It is still alive, just. It is clearly mortally wounded.

Illithir, feel free to make your Eldritch Blast attacks, but I will say up front, as the last peryton is so badly wounded, that literally any hit will kill it. So if you roll a 13 or more please do describe how the last one dies.

Also, for clarity, my description of it collapsing is just fluff, mechanically it is not Prone.

Notes: Rolled 10 and 17 on the Eldritch Blast, so chicken for dinner. Or would it be venison?

 He heard the song of battle before he could see what happening. The voice of the horrors readying themselves to fight, the roar of a companion, the steel of the others, the echoe of a bowstring. Preludes to a spectacle of death. By the time Ilithir arrived on the upper floor a single enemy remained. He unleashed the crackling energy centered on his hand and two Eldritch Blast cut through the air. The first, impeded by his own running, goes over the head of the peryton. The second, through, hits true.

A strand of silver that violent collides with the monster’s eye, cutting its way inside the head. The chimeric body tenses for a moment before going limp. There was no cry of pain, no blood. Instead, a fillet of smoke raises on the point of impact. The elf looked around, trying to make sure there was no danger. Part of him could not believe how successful the offensive had been.

It was a rare thing for Ilithir to thank the gods, but at that moment even he could not help but to do so. Those were dangerous enemies and the only attack to attack, his, was not one to be missed. They stood alone amidst the debris.

“Should we start to worry about a peryton dad?” He said half-jokingly, feeling victory was enough to allow for a pessimistic thought.

Still somewhat covered in peryton intestines, Thurodim gives Ilithir something resembling a smile and a shrug as if wondering if the elf's magical cleaning services was still available. "Dad's often leave." The massive half-orc mutters, then looks around the nest, trying to determine if this was the home for more peryti than the four they already killed. 

Perception: 18
Survival: 12

In his search, carefully making his way around the collapsed roof turned giant nest, Thurodim sees bones scattered among timber and tile, dried bloodstains marking this as a place of butchery. Food for the perytons, presumably. 

As he approaches the nesting area of the peryton who remained grounded, its now hollow head still gently smoking from Illithir's magic, he sees a glint among the old wood and new branches which have been brought here. Standing over the remains, he looks past it to see two eggs. They are each about the size of the average humanoid head, tapered to a point, and a dull metallic grey colour speckled with brighter, almost steel-like flecks.

"Eggs..." The massive half-orc growls, fearing they will grow up monsters to rip the hearts out of innocents, but he can't quite bring himself to smash them. "...you decide what we do with them." He continues with a deep sigh, motioning to the eggs.

Ghurr looks at the eggs and nods his head back and forth a few times.

"Eggs not dangerous," Ghurr says but then shrugs. "But not stay eggs for long."

He looks around and up at the sky.

"Big eggs make big lunch though," Ghurr says and, as if on cue, his stomach rumbles.

Ghurr raises his furry eyebrows at the others seeing if anyone objects.

"I don't care what we do with the eggs, so long as they are gone," Mala says. She takes a brief look at the now dead creatures. "Not so sure about eating those eggs myself. But feel free."

"Big omelette." Thurodim says with a chuckle, picking up the eggs to put them in his backpack. "Mission completed now, or should we investigate more?" He says, looking around at the others in the team, scratching his black beard.

Mala hesitates as Thurodim asks about their mission. Finally she speaks up.  "I think we completed our main task certainly. Should we be worried about the broken roof? Given the prisoner. Is he still securely held?"

She stows her longbow at her back, ready to head back down.

Ghurr smiles as Thurodim slips the eggs into his pack. Then he cleans the blood off the end of his glaive and gets ready to head back down.

"How you think bad deer birds see tower to make nest?" Ghurr muses. "Did they go to giant grave too? Or prison wizard call them?"

"Maybe there was an accident here, big momma crashing onto the invisible roof and decided to make it a nest, or...maybe as you said something lured it here." Thurodim says with a nod to Ghurr.

Ghurr nods a few times then either leads the way back down the stairs or follows who is already there.

Mala follows Ghurr back down the stairs.  She waits until everyone is gathered down there to say something. "I feel like we should make sure the prisoner is secure. But I have no idea how. I fear us more likely to release the person than learn anything."