Chapter 1: finding the Tomb

When Stone block were rising those of you who were curious enough to immediately move closer felt a poisonous gas coming out of the corridor, but mixed with fresh air was not strong enough to do you any harm.

When Zean takes the first of cubes to immerse it in the oil, the basin bursts into flames when you approach it holding the cube. Flame goes out if/when you move cube away - it is easy to conclude the flame is magical, though it does produce heat and light just as natural one.

Tinkara flies over to the smaller passage. Does the flame go out of you move the cube away from the basin? If not, I would say the cubes don't need to go into the oil. I'd also guess that we should light them all before trying the cubes in the sockets again. And I'm definitely in favor of using magic to insert the last one, just in case.

Zean back ups quickly so not to hurt himself. And to be sure how it all works he tries to move cube of animal closer to its enemy’s basin - "maybe they are neutralising each other." if that won’t help: He gets back to others and reports his recent findings. Also thinking if the magic hand could be the solution for every dangerous thing…

While the others are messing around with the Boxes. Vatoris tries to get a better understanding of how the Stone Slap trap works.
Hoping to Prevent it from happening again...
"How is it going over there? Figuring anything out?"

Thad steps over to Vatiris. Offering kind investigatory assistance!
That one part on the stone trap there, how might that work? That could be something, right?

Zean assures holding Moa (jaculi) cube it only fires up basin next to Moa (jaculi) and do not affect Wongo's (su-monster) one.
Same with Wongo cube - it only fires up Wongo basin.
Either way fire ends magically when you move each cube away.

Vatoris discuss with others what they have seen and concludes what the rests have concluded - when last of 8 cubes were put in and released it magically triggered stone block to start moving. There are no mechanical triggers. You would also expect that no more sand/stone be falling down when you trigger it next time as it remains on the floor.
As for source of the gas - you have no idea because you never saw anything, but you remember Zean suggested it may have originated from the small holes in each skull's mouth. But that's just a guess

Maybe we're barking up the wrong tree. What if the sockets are a distraction? Since we can't keep the oil lit if we move the cubes away from the oil, what if we put the cubes by each basin so they're all lit at once? Remember, "In darkness, it hides".

hmmmph Sounds like a plan to me.

Throgin goes back to the clearing and starts looking at the gargoyles again...

"I agree... again. Let's put them in the correct basins for the species. Maybe the lighting up will be enough... and if not, we will take them out and try again to insert them in opposed sockets - this time anointed with oil. Magic hand - anyone?" - Zean asks with big smile looking meaningly at Vatoris - "Don't look at me. If they would throw thunderstorms - I would do it. But I'm not so much into the fire... and I like my hands..."

I don't know that the blocks need to be IN the basins. Perhaps just having them close enough to light the oil would suffice.

Vatoris does what he is asked. He grabs the cubes with his mage hand and holds them into the fire. "Still think we are missing something...This is just taking too long. That has to be another way."

Everyone stay out of the small long tunnel, while Vatoris take all 8 cubes except flail snail cube (it stays in bag of holdings) and put them next to each respective basin, firing them up.
He try to stay close to exit (as much as mage hand reach allows). When all 8 basins burn and nothing else visibly happens Vatoris manipulate each cube putting it into a basin of opposing god figure, for example putting Moa (jaculi) cube into Wongo's (su-monster) basin: it cause Moa basin fire to stop, but affect Moa's cube in no visible way.

"So let's put the cubes INTO the proper basins so i.e. : Moa cue into the Moa'a basin. All of them, at once. Will you Vatoris?" - says Zean.

Tinkara flies over to the larger passage to see if anything changes there when all the basins are lit.

Vatoris, mechanically follow instructions given, but keep trying to understand .... what are we missing?

The enemies oppose... The enemies oppose he quote the obelisk and suddenly realize this reflects the Onlu Legend they have learned in past few days:

He quotes parts of the legend:
Wongo the su-monster found out how Moa had betrayed him, he vowed to catch the jaculi and eat him up
and
The zorbo and I'jin the almiraj became terrible enemies
and now everyone remember that also
Kamadan chased Nangnang the grung
while
Kubazan the froghemoth chased Papazotl

But it was Unkh the flail snail that saved the day in the legend...