Oorr, you aren't familiar with the kind of magic that would be able to send a creature back to its plane of origin, but Belwar has a healthy knowledge of higher level spells such as Banishment, or Dispel Evil and Good, that could do the trick.

Any other questions for the Burrow Warden?

Grimnir, who was silent and was waiting for his turn, takes his journal from his bag and looks at his notes.”

"Hum, let’s see... I have 1 or 2 question if you may. We are about to meet some wererats from the North, do you have any information on them? Also I heard about a large cavern known as Entémoch’s Boon, somewhere around here, do you know where is it ?
But most importantly, we are on our way to the surface, do you know the path?"

Grimnir, then closes his journal, and stares at the ghost.

Quote from RonanKP >>

Grimnir, who was silent and was waiting for his turn, takes his journal from his bag and looks at his notes.”

"Hum, let’s see... I have 1 or 2 question if you may. We are about to meet some wererats from the North, do you have any information on them? Also I heard about a large cavern known as Entémoch’s Boon, somewhere around here, do you know where is it ?
But most importantly, we are on our way to the surface, do you know the path?"

Grimnir, then closes his journal, and stares at the ghost.

"Whoah now, that's a lot of questions all at once. Let me see... The wererats have been here for a long time, but I'm afraid I don't know what their goals are. Some in the city think the wererat community should be welcomed, they were once deep gnomes after all. Others think they are a nuisance and should be eliminated. As far as Entemoch's Boon is concerned, I only know it's West of of town a ways. They say there are way markers that will guide those with the tenacity to find them towards the boon, where ancient elementals were once summoned. Of course, as long as Ogremach's Bane exists, summoning elementals will be a risky endeavor. Ah, and now to the real issue. Getting home." The burrow warden turns to look down the hallways behind you, then behind him, and then finally speaks again. "You're doing a lot of good in this town. There are rumblings of a battle to come, a force of great evil dwells in the Northwest, and you are just the type of heroes that could turn the tide. But, since you asked, my wardens do know of ways to the surface, not far from here. I'm afraid that's all I can say for now, but when you're ready to leave, let me know, and we will show you the path. I'm afraid that's all I have time for now. Thank you for laying these gnomes to rest. I'm sure we will meet again soon." With that, Jadger dissipates, waving as he vanishes, and leaving you alone in the catacombs.

Once silently thanked the Warden, Oorr and Zippy lead the party toward the wererats den, scouting just a bit ahead in the shadows.

Oorr: Stealth check: 11; Perception check: 13
Zippy: Stealth check 24; Perception check: 10

Grimnir cracks his knuckles. "Very well, let's go. From what I remember, one of the leaders wants them dead, the other one wants to parley and see if  they could join the city. I guess we'll have to talk."

"Oorr, remember. Someone warned us to walk on the side of the road, not in the middle. Maybe some traps ahead?"

Oorr, you and Zippy lead the group out of the catacombs, and head West towards the door that leads to the edge of town where the Goldwhisker clan has been blocked off. You inform the guards of your intention to investigate the warrens, and they unlock the door to let you in (Area 5 -> 23). Having been warned, you and Grimnir take a look around and do notice a trap set in the middle of the room. A sheet of canvas carefully disguised to look like the rest of the floor. Using this knowledge, you carefully walk along the edges of the room, avoiding the pit trap. 

The hallway before you branches off to the South and North. The area smells of decay and mold. Drips of water from a broken cistern can be heard in the distance. Before you can decide which direction to go, a creature emerges from the stone wall in front of you. It doesn't crawl through, or break through, it simply appears, as if it was a part of the wall or just passing through it. It has three arms, each of which are tipped with a large claw, and stands on three squat legs. It has a single eye, and a large maw atop what you would consider its head. It spies you, and emits a rumbling sound.

 It begins waving it's arms around in the air, and moving toward the party.

Oorr throws at the weird two zircons (50 gp each) and watches the reaction. "We are friends!" (Primordial)

OOC Does Oorr know what it is? Arcana check 17

"By Moradin, what is that creature ? It is quite ugly"
Grimnir keeps his distances with the thing and waits to see if Oorr's tip is working.

Brox stays back. She doesn't even understand that words have been exchanged. She just looks at the moving maw somewhat in awe, almost frozen. 

Quote from filcat >>

Oorr throws at the weird two zircons (50 gp each) and watches the reaction. "We are friends!" (Primordial)

OOC Does Oorr know what it is? Arcana check 11

 The monster grabs up the Zircons and tosses them into the mouth atop its head, where you hear a grinding noise, and see shards of the crystals churned around as the creature eats them. Following a loud belch, it rumbles a "Thanks. Any more?" to Oorr, who it seems to understand. Oorr, you don't know much about this creature, but you think it's what is called a Xorn. Apparently it likes to eat gems, but does not seem hostile. More like a beggar.

”Perhaps, I have more. But I would like to ask you a couple of questions. You seem a earth creature. Do you know where the Entemoch's Boon is?"

Oorr will watch the Xorn's reaction before asking any more questions.

"How much more? Boon is far from here. Need many gems." It seems to be eager to get more gems from you, and takes few steps in your direction. 

Oorr takes an amethyst from the Bag of Holding and shows it to the Xorn... from a distance.

"See, I have some more, this one is particularly tasty. If you can take us to the Boon, I can give you two of these, and some diamonds, too. A great feast, bested only by mountain fish from the Unicorn's Run. What do you say? Can we be friends?"

"Yes, yes, take you there. You feed many gems." After saying this, the Xorn, turns and rushes headlong at the wall to the West. Instead of colliding with it, it moves through the wall as if it wasn't there. A moment of silence passes, and then the Xorn sticks its eye through the wall to stare at all of you. "Follow?"

"hummm...Oorr ? What is going on ? I do not speak this weird language."

”Well, it seems the winds are in our favour. The kind creature you see is taking us to the Boon. It just need to eat more gems afterwards."

Brox listens to Oorr's explanation. "I don't have any gems. But remember, there were gems with the last ghost that we... ehm.... helped."

"I have enough gems. I think."

And so Oorr follows the Xorn.

Grimnir secures his pouch, having no intention to give his treasures to this creature, and follows Oorr

The Xorn phases through the wall, but when you try to follow it, Orr, the rock is solid. The creature doesn't seem to understand you cannot follow it directly through the rock. It appears to have gone in a Western direction. The passages in this area of the city head North and South (or back East where you entered.)