I have you all in a " + " alignment with Erven in the east, Bert in the south, Talion in the west, Onyx in the north.  Sho in middle.  Lucky Bear is right above Erven.

@Erven
Looking in, you notice all the things mentioned before.  You feel an overwhelming sense of wrongness in this room, like you can feel things - bad bad things - have happened here that serve to offend anything good.  The only difference is the room is bigger than you thought previously - likely a trick of the eyes playing on the mist and such.  Everything else remains the same.  

Quote from Ereshion >>

If space permits, Talion will move forward to hammer the piton deep into the doorframe (wall or floor), trying to ensure the door will remain open.

 you do so, getting in front of Erven for a moment.  The hammer's pounding rings off the walls and bounces back to you more times than it should...great acoustics in the room - Bertolt, nods approvingly...  The door is effectively stuck open and you're unsure if you could even take the piton out if you tried...

Erven nods to everyone, approves of the piton in the door, and motions to proceed inside.  He will stay with his back against the wall, angling toward the portcullis.  If light is sufficiently low, he will attempt to do so and blend into the background with stealth.  He will try to stay out of the water and along the ledge.

@Erven
No problem, you walk along the outer edge slowly, go ahead and roll a stealth check.  You get to the portcullis.  Is everyone following?  What do you do next?

Erven stealth : 14 

From that vantage point, sees if there is anything else in the room, anything moving.  He will wait until he looks, then will give a thumbs up sign for others to enter if nothing is evident.

Quote from Twombley >>

Erven stealth : 23 

From that vantage point, sees if there is anything else in the room, anything moving.  He will wait until he looks, then will give a thumbs up sign for others to enter if nothing is evident.

 Lucky Bear follows after you quickly, hopping onto the ledge and sniffing as you both go towards the portcullis.  At one point, you reach down to touch her and she is looking up at you.  She licks your hand a few times.  You think that with a bit more time and training, you might have a powerful animal companion beside you.  From your training as a ranger, you know sometimes animals can be trained as warriors too.  No reason to think Lucky Bear couldn't be trained....You know for sure that Lucky Bear would likely try to follow your orders...

  Nothing is moving other than the mist, which hangs above the water...

Erven motions to Lucky Bear to go get the others, tug on their legs etc. & encourage them to come into the room.

Creeping forward, his usual stoic self, Onyx grips his blade tightly, occasionally rubbing his holy symbol for good luck and reassurance.  The chanting was starting to get to him, but he did his best to steel himself.  The end of all this was ahead.  He could sense it.  As they pass the alcoves and artifacts, he eyes them.  These were important, monetary value aside, and shouldn't be left there, but that too would have to wait.  He listens wordlessly at the cursed soul, rotting past his natural death.  He was glad he did not have to end the wretch's misery himself.  Erland. He tries to remember the name.

As they enter the ritual chamber, he lingers near the secret door for a moment longer, taking a deep breath and opening his mouth a little to activate Divine Sense (and to check in with his Blindsight.)  If nothing triggers, he will try the winch on this side of the portcullis.  His shield is strapped to one arm, his sword is sheathed for the moment.

Once Erven sees Onyx enter the room, he nods to him, waiting for his reaction and evaluation.  If nothing is seen, if he keeps moving to the portcullis, Erven will help him turn the winch to raise the portcullis.

This would put Erven at around C8.  He motions for Lucky Bear to return to his side.  

(Sorry busy day at work and now my notifications are more then a day behind...)

Bertolt will stay the back as he normally does, not wanting to step on the toes of his more melee oriented companions. He will raise his latern to give more light for them, keeping his eyes trained on the portculis.

Talion moves to F2, checking back the way they came. He waits a few moments then moves forward to F3 in order to look into the room.

Sho will move into the water chamber and follow behind Erven and Onyx, about C4. 

Quote from Twombley >>

Erven motions to Lucky Bear to go get the others, tug on their legs etc. & encourage them to come into the room.

 Roll animal handling with advantage, DC15.

Quote from Ursus_the_Grim >>

...As they enter the ritual chamber, he lingers near the secret door for a moment longer, taking a deep breath and opening his mouth a little to activate Divine Sense (and to check in with his Blindsight.)  If nothing triggers, he will try the winch on this side of the portcullis.  His shield is strapped to one arm, his sword is sheathed for the moment.

 As you close your eyes and open your mind to the light of Lathander, you are immediately hit with a sour smelling odour and a feeling of terrible wrongness inside the chamber.  Scanning the room, you realize that horrible, gruesome things have happened in this chamber - enough to make even gods weep.  You intuit the intentions of these cultists but the methods they employed were severely misunderstood... Evil hangs in this chamber like a wet veil, sticking to and marking everything that enters.  This place has been desecrated by the misguided actions on the cult.  You also get a strong pulse to your right, as you survey the room.  Something in or near the refuse pile is giving off a strong odour - rotting flesh, sulfur, the scent of decaying fruit.  From your experience, something undead lurks around that area, although - oddly - nothing to suggest evil or good.  

MAP

Erven animal handling :  21 

Erven tries to calm Lucky Bear and will give him a scratch on the head if he gets close enough, but he must be unsettled by this room and thrown off, anxious.

Onyx's head spins for a moment, reeling from the oppressive vileness of this chamber.  Not approaching any further, he points to the refuse pile.

"I think 'She' is over there, slumbering or waiting I am not certain."

Glancing warily over his shoulder, Onyx will continue moving to where the winch is (on the other map anyway) and attempt to raise the portcullis on this side.

Quote from Twombley >>

Erven animal handling :  11 

Erven tries to calm Lucky Bear and will give him a scratch on the head if he gets close enough, but he must be unsettled by this room and thrown off, anxious.

 Lucky urges her head towards your hand, grateful for the scratch. When you take your hand away, she forces her head again to your hand, apparently you’re not done petting her!  Finally she moves off to sniff at the water before drinking it, and sniffs at the dais....

Quote from Ursus_the_Grim >>

Onyx's head spins for a moment, reeling from the oppressive vileness of this chamber.  Not approaching any further, he points to the refuse pile.

"I think 'She' is over there, slumbering or waiting I am not certain."

Glancing warily over his shoulder, Onyx will continue moving to where the winch is (on the other map anyway) and attempt to raise the portcullis on this side.

 You move to over near Erven and use the wheel. The portcullis groans in protest but you’re able to raise and hook it so it doesn’t fall. It seems securely held by the mechanism...

Seeing that the portcullis is now up, and the secret door is jammed, Talion is a little less concerned about being attacked from behind. He moves to inspect the portcullis, trying to work out how he might jam it as well.

"Don't jam this one." Onyx warns Talion. "When She wakes up, she'll be angry.  Might want to drop it on her."

He points out the hook used to keep the portcullis raised.

Talion smiles and nods, a spectral hand appearing briefly, "Would that be strong enough, do you think? Or should we look for other means?"

The hand quickly disappears and he glances around, "Do you know who she is?"

(( I assume portcullises are actually quite easy to drop, at least based on old movies...does Talion agree? ))

Bertolt will stay in place by the portcullis, setting the latern down so that it will continue to give off light while allowing him full use of both hands. His eyes stay trained on the dais incase something comes towards them from it.