Swiper simply starts poking at the gith that dropped to the floor to ensure that he was alive, all the while curiously watching Lydia destroy the sphere.

Nirzeg blindly tries to ward the bothersome Kenku. "Leave me.. to... catch... my breathe.." He groans while flopping onto his back, so that he faced the ceiling. Given a few moments to look lazily around, he squints up at the tunnel nearby. "... Of course." The Githyanki mutters, and then aloud says, "I doubt I'll able to shrink Big Blue or Big J enough for long enough to enter that. So, I presume we'll be leaving them in this room? Or have one of you found it to be a dead end?"

Lydia meets the granite sphere as it's being rolled back up the hallway. It quivers, then cracks, then ruptures. Chunks of granite fall to the frozen floor as the inside of the sphere bursts. 

The stone giant statue pauses, then turns and walks back towards its alcove at the south end of the hall.

After this happens, the walls of stone that appeared in each of the archways disappears completely. The archways on either side of the hall are now unobstructed.

Quote from Orileo >>

Nirzeg blindly tries to ward the bothersome Kenku. "Leave me.. to... catch... my breathe.." He groans while flopping onto his back, so that he faced the ceiling. Given a few moments to look lazily around, he squints up at the tunnel nearby. "... Of course." The Githyanki mutters, and then aloud says, "I doubt I'll able to shrink Big Blue or Big J enough for long enough to enter that. So, I presume we'll be leaving them in this room? Or have one of you found it to be a dead end?"

 Harshnag nods. "Don't let me spoil your fun! I am not sure where this fissure leads, but if you wish to explore, I am happy to rest here and mend my wounds. I can also watch the horses." 

Rasa looks particularly dubious at the thought of going through the fissure.

"You don't have to go as well, Rasa. In fact, if you wouldn't mind exploring the little whatever the **** -- cubbies? I guess ****'n cubbies. Look'em over. Maybe some jackass actually managed to get to the back, only to starve to death or some shit. Worth a shot." Nirzeg offered. Then with a final huff, he gets back to his feet, cracks his neck, and then looks expectantly to Derrikoth to start leading the way.

Lydia hangs out in the back with Swiper. "It is very fortunate that those spells worked. They were the most powerful ones that I could cast."

Derrikoth pats Josephus's neck to calm the horse—and himself—down, though he stops when he notices Nirzeg looking at him. He remounts Josephus, riding deeper into the structure, trying to keep an eye out for any more boulders.

You are able to explore the rest of this hallway while Harshnag rests. Rasa seems content in his giant mountain goat form for the time being, acclimated as it is to cold environments.

The other rooms contain stone "beds" just like ones before, and are otherwise bare (save for the frost that clings to every surface).

There are three obvious options for exploration/searching: 

1. Back to the main Temple structure (where there are more doors to choose from).
2. The stairs at the south end of this hall, which appear to lead up to another level.
3. The 10' x 5' fissure in the room where Harshnag is currently resting, which likely leads into the mountainside. 

Where to next?

"Not quite what I... Ah, **** it. I should've figured." He'd say, remembering a certain Dragonborn's attachment to a certain horse. For his part, the Githyanki followed along at least part of the way, but fairly quickly directs Zeek to help in scouting the rest of the area. Once everyone else has convened once more, he returns to the fissure and leads the way this time in its exploration, trusting his curt motion for the others to follow to be enough.

Much as before, Zeek is made to fly at least fifteen to twenty feet ahead of the party to better alert the party of any dangers lying ahead in the fissure. That is, such was his somewhat unspoken intent, unless others might wish to voice other plans.

Zeek's Stealth: 22.

Zeek's Perception: 15.

The floor here is icy and uneven. (These tunnels are considered difficult terrain, unless you have a trait such as the spider climb spell.) A thin layer of frost coats the walls, floor, and ceiling. It is totally dark here. 

// Not sure what I was waiting for! But here you go! //

Grapple attempt: 8 (Need Zeek to roll opposed Strength/Dexterity)

Crawling into your sources of light is a creature with multiple eyes of blood red. White fur covers its body and eight legs. It's the biggest spider you've ever seen, and it's trying to eat Zeek.

From out of the darkness comes two webs, one aimed at Nirzeg, the other at Derrikoth. Following the webs, moving into the light at an alarming speed, two more enormous spiders make for you, crawling sideways along the icy walls. 

Web Attack: 25 Damage: (none), on a hit Derrikoth is restrained by icy webbing. 

Web Attack: 22 Damage: (none), on a hit Nirzeg is restrained by icy webbing. 

// Players up! You are single-file, the tunnels are 5 feet wide by 10 feet high, and it's difficult terrain throughout. Between the lot of you, you should have enough light sources that darkness isn't an issue this close up. Have fun! // 

Zeek Acrobatics(DC 8): 11.

Zeek just narrowly escapes the clutches the spider, and promptly gtfo as soon as possible. Though a tight squeeze, being the tiny body critter that it was, he just narrowly slips between the gaps, and well beyond the pair currently struggling in their bonds.

Seeing this, Nirzeg stops his struggling long enough to bark out a, "Hey! You were supposed to alert us ya dumb familiar! Gah! When I get my hands on you-...!" The struggles renewed, but to little avail. So in giving up, the Githyanki drops his torch, and through a great deal of effort, manages to force his hands. "Embrace the Flames of Gehenna!" His palm glows brilliant green, then from its center leaps forward a cone of Green Flames to wash over the first two spiders.

Action: Cast (3rd level)Flames of Gehenna, inflicting 15 fire damage to the two spiders closest to him. Dexterity Save(DC 14) for 1/2 damage.

Lydia casts Toll the Dead on one of the spiders. It must make a DC15 Wisdom Save or take 8 necrotic damage.

Dex save 23

Dex save 17

Wis save 15-1

Swiper wasn’t the biggest fan of spiders, and he was glad that he wasn’t the target to be their lunch for today. Regardless, he knew he was gonna have to help get rid of the problem somehow, so he raises his crossbow and shoots at the nearest spider!

Attack: 20 Damage: 10

Sneak attack (if applicable): 8

The response against the spiders is chaotic, and the uneven walls of the cavern cause the initial attacks from Nirzeg, Lydia, and Swiper to miss their marks. However, Nirzeg is able to burn away the webbing from his body with the green fire spell.

Rasa conjures a flaming bonfire right in front of Nirzeg, under the white spider's hairy body. 

The white spider tries to avoid it... 23

The big spider, extremely sensitive to heat and light, avoids the fire with almost preternatural instincts.

// Derrikoth is up! //

Derrikoth grunts, swinging his sword as best he can to try and break free.

Attack: 14 Damage: 10

Attack: 10 Damage: 4

The icy web breaks when Derrikoth cuts through it with his sword. 

(Nirzeg and Derrikoth both take 1 cold damage this round)

The spiders surge forward. They crawl overhead, and move to attack Rasa, Nirzeg and Derrikoth. 

Bite Attack vs Nirzeg: 12 Damage: 8 piercing, and on a hit, make a DC 11 CON saving throw. 

Bite Attack vs Derrikoth: 24 Damage: 11 piercing, and on a hit, make a DC 11 CON saving throw. 

Bite Attack vs Rasa: 11 Damage: 11 piercing, and on a hit, make a DC 11 CON saving throw. 

A fourth spider rounds the corner and spits its web at Nirzeg...

Web attack vs Nirzeg 16, on a hit Nirzeg is restrained.

// Players up! It's getting crowded in here. //

Rasa makes a CON saving throw: 13

Reaction: Cast (1st)Barrier, raising AC temporarily to 23 and warding off the web.

Scowling, Nirzeg sweeps his hand through the air as if batting aside a minor nuisance, and a call of "Negora!"As webbing splatter against an invisible wall, draws Giyan as he turns on the spiders above. "This... Chill... Unnatural... Do not linger by them if you can for long." He calls out in warning as he swung at the one roughly behind and above him with a vibrating blade.

"Zeeek!" A plaintive yeowl echoes through the tunnel. "Help ya useless ****!" A defiant yowl answers Nirzeg back. And yet, the spider in the back suddenly has to deal with an agitated cat swiping at its eyes and flying about its face in agitation.

Action: Cast (Cantrip)Vibrating Blade - Attack: 15 Damage: 8 of magical slashing and thunder damage and additional 12 thunder damage for volunteering movement.

(@Cherri: You're getting advantage on the spider to the far back)