Also I accidentally put 9 instead of 6 for the chuul's attack bonus, although I don't think it matters in this case.

One of Spark’s stones hits the golem in the head and spears to have dazed him a bit. But then the electric discharge of the stone sends a spasm through the golem and invigorates it, spurring it on! However, it only hastens into the ready pincers of the chuul which grabs it firmly with both. While grappled - twice - by the chuul, the golem does not appear to suffer any ill effect from the attack. Its resilient skin and soft - whatever there is below the skin - safe it from any damage that the chuul can inflict on it. On Spark’s command, the chuul slowly drags the golem towards the chasm, which get the Tiefling’s attention, who had resumed his ritual and, judging from his expression, had not expected that his attention would be required so quickly.

(Letting go from the grapple will not require an action but it’s not enough that the chuul is next to the chasm to let the golem fly. It must be moved there over the chasm with the halved movement. I expect next turn you could get it close enough. We wait for Minty, then goes the other side.)

updated Map:

The flesh golem notices the plan of the chuul but can't do much to avoid the grapple and to be dragged along. He tries another strategy altogether, and attempts to grapple the chuul himself. The Necromancer, disturbed by the event, reaches out with one arm as if he wants to grab the chuul and, by will of force, a ghostly hand materialises. The hand hovers to the chuul and tries to grab it and draw out the chuul's life force.

The golem's Athletics: 8 versus the chuul's Athletics: 17

Attack (Chill Touch on chuul): 13 Damage: 8

Initiative: Minty & Spark & Chuul || Flesh Golem & Necromancer

Spark runs to S25 and casts Cure Wounds on the chuul, trying to keep it alive.  Healing: 10

She uses the rest of her movement to run to S27.

The chuul drags the flesh golem over the chasm (somewhere around Q21) and lets go.

The chuul calms under the healing touch of Spark's hand ever so slightly and uses the newly gained forces to drag the golem further towards the chasm. It appears that the chuul meets resistance from the iridescent light tether that pulled tight due to the golem increasing its distance to the relic. The chuul tries harder and the bubble around the necromancer deforms and elongates to give more way for the golem albeit not much. With a last powerful drag the chuul tries to finally move the golem and succeeds abruptly with the tether being ripped apart. With more momentum than it had anticipated the chuul disposes of the golem in a wide arc deep into the chasm. The iridescent light of the tether vanishes and so does the bubble around the Necromancer, which stared open-mouthed at the happenings unfolding in front of his eyes before letting out a high pitched shriek in way of complaint. 

Initiative: Minty & Spark & Chuul || Necromancer

(We wait two days for Minty and then I post the Necromancer.)

Minty takes careful aim at the Necromancer and lets a bolt fly.

Attack: 22 Damage: 14

Sneak Damage: 16

The necromancers shriek stopped abruptly when Minty's bolt beat the air out of him. The bolt hit him with such force that it nearly toppled him and his expression of shock turns into one of fear. After catching his breath, he starts a slow incantation and with raising his two outstretched arms slowly up, he conjures greenish-yellowish vapours from the cavern floor that coalesce into one giant cloud of poisonous fog. Then, footsteps sound towards the cave exit. 

Cast Cloudkill DC 15 Con save for half damage, otherwise: 24 poison damage (Note that the chuul is immune to poison.)

Initiative: Minty & Spark & Chuul || Necromancer

Just from the one powerful hit by Minty, the necromancer looked seriously hurt.

Map:

(Where is the fog located?)

(That’s the large green area overlaid your positions. It obscures view heavily. Wait, do you see the map in my previous post? For me, it’s visible.)

(I didn't see your last post with the map when I posted before.  It's there now.)

Spark's Constitution save: 21

Quote from LaOtraVacaMorada >>

(I didn't see your last post with the map when I posted before.  It's there now.)

Spark's Constitution save: 21

 No problem. I had sometimes problems seeing other people’s uploaded images, so I wanted to be sure and rule that out.

Spark avoids the worst of the poison, but knows she can't safely remain in it for long.  She uses her bonus action to cast Expeditious Retreat, but this is no time for retreat.  She runs forward towards the sound of the footsteps, stopping at T35, and uses her sling to launch two of her Magic Stones at the necromancer.

Attack: 13 Damage: 12

Attack: 21 Damage: 15

The chuul Dashes to V35 in pursuit of the necromancer.

While one stone was deflected by an invisible barrier, the other hit the necromancer at the side of his head leaving him visibly dazed. 

Constitution save:  17

Minty rushes forward choking on the poisonous smoke.  He pursues the Necromancer easily catching up with him.  He drops his crossbow and takes the uncommon action of drawing his rapier.  He casts a spell of his own (the only one he knows) and attacks the Necromancer.

Attack: 12 Damage: 5

Booming blade damage: 7

Additional Thunder damage if the Necromancer continues to move away: 8

Minty's rapier drives deep into the necromancer's gut, who tried to stop the blade with both his hands while standing there wide-eyed and unbelieving. Then his eye twitched and a tiny bat flaps out of the cavern and it goes straight for Minty's neck in an effort to distract him! At its final breaths (he has 1 HP left), the necromancer uses the opportunity to grab Minty's throat with an ice cold hand.

Attack: 14 Damage: 13 necrotic, if he hits, he heals 6.5 HP

Initiative: Minty & Spark & Chuul || Necromancer

Spark makes two more Magic Stones and slings them at the necromancer.

Attack: 17 Damage: 9

Attack: 13 Damage: 10

Only one of the stones finds purchase but it does to great effect, the necromancer goes down. His hand losing its grip on Minty’s throat and slides slowly to the ground where he remains motionless. 

(we’re out of initiative and this was the last encounter. When you post what you want to do, please also post a perception roll.)

Perception: 24

As soon as the threat has been dealt with, Spark returns to Rizo, taking the chuul with her.  Lacking the physical strength to carry him herself, she tries to get him onto the chuul's back so that they can take him back to Dolsela safely - assuming that, indeed, that is where the exit leads.  Or, failing that, get him to Isivunguvungu, who probably knows some way to help him.

"You can't die on me now, Rizo.  It doesn't count if I only become more powerful than you because you're dead."

You remember that in the previous cavern with the mushroom forest there was an exit to the forest of wonders. You can't be sure whether the Zurkhwoods will notice you and try to stop you but that would be the fastest way back to town. 

(Let's see what Minty rolls for perception before I describe the cavern.)