The BFOAGWGH

I carefully bring it out and open it, checking for traps as I go

Preception with thieves tools 11

Disarm/Open with thieves tools 26

 XiaoLong high fives her fellow fighters (low fives in the case of Ro and Twiglet) and looks in the room for anything valuable:

Perception 20

The chest is not locked. Opening it, you see the remains of ancient bandages and dried herbs. Lifting the layer out, you find two long slots underneath. One side has been damaged by the bed falling on the box and is filled with broken glass. The other however holds a sealed potion bottle. 

 Xiaolong extends her arm towards Twiglet and proposes to carry the precious elixir.

She then heads towards that strange noise, inviting the rest of the party to follow.

"Twiglet, can you ask Ro what it has seen or heard over there ? I'm not afraid of danger but would prefer we know what's ahead of us"

[A sound like peeling a huge bandage. Not a nice sound.]

If we're going off in that direction Ro will try to stay at least 10' ahead of the torchlight, stopping at each intersection to try to figure out which way the sound is coming from.

Stealth: 19

Perception: 10

You wander through the mine shafts narrowing down the source of the sounds. You believe you have got it trapped down a deadend. As Roars moves forward silently, she see that the end of the shaft looks very different to the others she has seen. It seems to be shifting and moving with a pale orange colour.

Ochre Jelly Perception 6

Ro backs away very slowly and doesn't turn around until she's almost bumped into Twiglet.

[I find a...jelly? And it moving?]

[Do you want I try to poke it? Or throw a rock maybe?]

Tallanvor explains to the group that he's seen this creature in the past and that they should not use slashing weapons or lightning on the creature or it will become much more dangerous to them. He turns to Twiglet

"Be ye not afraid, young one. We need yer strength in the battles to come. Blessed by the light, I am, and will make sure ye come t' no harm. But we could use that blade o' yours. If we take this thing unawares, we may save ourselves some trouble."

Once combat starts, Tallanvor casts https://www.dndbeyond.com/spells/guiding-bolt. 

Attack: 21 Damage: 24

Attack: 13 Damage: 16

On hearing this Ro switches to a pair of daggers. When combat starts she's going to run forward, make two stab attacks, and then move as far back as she can.

1st Attack: 24 Damage: 7

Offhand Attack: 11 Damage: 4

 Jelly Initiative 14

A flash of light shoots from Tallanvor's hands striking the Jelly. It recoils as if in pain and glows faintly.

Roars dashing in and stabs at it twice, both time leaving large wounds in the goo before retreating.

The Jelly is looking quite ragged.

Initiative: 10

Humblodt whacks the jelly with his shillelagh: 23 Damage: 10

"That'll show it we're not to be trifled with!"

The Jelly goes splat when hit with the shillelagh, but reforms itself slowly, with large gaps visible.

XiaoLong approaches the jelly to throw a couple of, hopefully, deadly punches:

Unarmed strike:  Attack: 21 Damage: 4

Bonus unarmed strike: Attack: 21 Damage: 5

The Jelly explodes under the deadly punches splattering the walls. It's remains drip sadly down to the floor and remain still.

Xiaolong inspects the room

Perception 13

Ignoring the lumps of jelly stuck to the walls, this mine shaft doesn't appear to be any different than the others in the area. The miners appear to have dug until they decided it was worth moving onto new shafts. If you head back east, you come across another shut door which you can hear crunching and snapping noises on the other side of, the same as was hear earlier. There seem to be two exits from the mines to the north which open into larger rooms.

Twiglet was looking at his small sword and daggers, wondering what on earth they could do and how you sneak up on a lump of goo...when the others spring into action, pummeling and stabbing the mass until Xiaolong explodes it with a flurry of blows. What a mighty group of heroes for him to accidentally team up with! Tallanvor's magic was truly a sight to see, the light literally exploding from his hands. What could possibly threaten these adventurers.

Twiglet creeps forward, alongside Xiaolong, to poke at the gooey remains and see if there is anything past where it had blocked the tunnel....though he has no expectations that a living blob would have any treasure

Perception 13

 Xiaolong walks towards the door, East, from where the crunching noise comes from.

"Twiglet, can you please check for traps and nasties on this door ?"

(Using Twiglet's Perception Roll from earlier)

Twiglet doesn't detect any traps. The door is also unlocked and can be opened easily