The ones you have used below the tower are stone.
Mulligan times a quick back stab against the hapless Goblin and kills it. She drags him to the window and dumps the body out the window with a small struggle.
Sorry about the mess Miron, do you think you could check the body over and hide it somewhere.
There is a troll sleeping by the front door with a huge barricade so I don’t think we will be getting in that way.
I am going to head upstairs to see what is at the top, back soon.
Elfstan will try to figure out a way to use Mulligan’s cord to trap a torch. The idea is for the cord to act as a tripwire pulling the torch down the steps. If this isn’t possible using the cord and possibly his iron spikes, he will move on to the meat of his plan. That is to use his flasks of lamp oil to oil down the upper most section of steps. They are steep and should make for a very nasty fall. If the oil can also be set on fire by a trapped torch, so much the better.
He has 8 flasks of lamp oil total, the GM can rule on if they are all in his pack or if some would be in his saddle bags. If he has them all in his pack, he will save one. Otherwise, he will use however many he has with him.
As Elfstan oils down the steps, he will leave a narrow path down one side for his own use if it’s necessary. He will extinguish all of the torches other than the one he trapped (if trapping isn’t possible, he’ll extinguish that one too). With the goblins nearby, he can use Sting for light.
In the short 5’ long section of goblin tunnel, he will quietly break the empty oil flasks and leave the broken shards on the ground. It won’t do anything to a troll’s skin, but it might slow a goblin.
In the last small section before the entrance he will look for a way to plant his six throwing daggers in the ground, point up and slightly angled towards the tower. Hopefully these will at least make a troll cry out in pain, giving us some warning if one is coming.
With that, he sneaks back to the rest of the company and informs them of what he found and did.
Miron buries the goblin tight against the wall of tower under the available debris.
Mulligan heads up to the second (top) floor. As he comes up he finds a wall of heavy curtains blocks off the windows and allows only dim light into the core of the floor. There is a large troll in this area with modified ballista that must be the huge crossbow described poorly by the animals.
The troll does not seem to see Mulligan immediately who ducks back down fast. Two troll accounted for, there must be two below. The ceiling looks to be stone supported by heavy wooden beams. It does not appear to be the best work by any means.
Elfstan cannot come up with a way to yank the torch onto the oil. He extinguishes them all after coating the stairs with 7 pints of oil. The flasks were not glass however, far too fragile and heavy to carry. They were leather by default. Beside the glass would not have bothered the goblins, they just stoop to get through as Elfstan recalls from the description of Bilbo being pursued under Goblin Gate in “There and Back Again”.
He sets the throwing knives and heads back swiftly.
Thoroncir, when he finds out all about Elfstan’s and Mulligan’s skulduggery, is going to be very impressed! 
Is the troll asleep and can I get to the ballista without the troll noticing?
If so, I will be disabling it. I doubt I could break the winding mechanism, so I will settle for partially severing the rope at both ends. Hopefully the first time he tries to wind it up, the rope will give putting it out of action.
I take it the ballista is too big for me to move quietly then, otherwise I could point it at a sleeping troll and pull the trigger. 
A coup de grace on a sleeping troll with a ballista - there’s a story for the inn afterwards. No-one would ever believe it
This troll was not asleep. Mulligan was somewhat lucky it did not see her. Time is ticking away, it is already getting darker out. The storm must be nearing.
I take it the ballista is not accessible without being noticed then.
The troll was holding the ballista in his lap in your brief look.
I wish someone had answered my question about trolls and a paralysis shot from an injection dagger. 
Hmm, it’s still daylight, somehow though I think trying to get it into sunlight could be tricky, nigh on fatal.
Better let everyone else know what I have found. Back to the window and out again.
Sorry, I thought I did and the answer is that it is extremely unlikely to work. PM me if I missed a question please. Sometimes it is hard to hold all the threads together.
Mulligan and Miron swiftly but carefully return to the group.
I probably missed it then
Time to tell everyone else what we have hidden for us in the fort.
The goblins should not be a problem and are more likely to run than anything else. The fun part will be getting the trolls one at a time.
Is there any spots were Elfstan, Mulligan, and Miron can set some trip lines? If not, the only other idea I have is some oil in front of the tower door to add to the chaos.
If there is time before Ghan calls lightning, Elfstan would like to scout around outside that house. When this battle is over, we’re going to need shelter in a hurry.
Mulligan & Miron might be able to set some trip lines in front of the door. The oil might prove more dangerous to the party then the trolls. Fire barely affects them compared to you fleshier creatures.
As to scouting the house, you are running out of time before the storm hits and then it gets dark enough for the trolls outside. You could scout it as Ghân begins casting in theory. You are invisible after all.
I was thinking more about making them fall over than burning them, but the trip lines are probably the way to go.
If Ghan things there is time, Elfstan will immediately head for the house just to take a quick look around the outside. He’s looking for easy ways in, signs of use, and anything really out of the ordinary. He just wants to be clear of the area before the lightning hits.
Final plans now. Lightning will strike the tower from Ghân in 19 minutes meaning the rains will already be starting probably and leaving plenty of time for Elfstan to scout and Miron and Mulligan to set a trip wire.
Who else will be heading up and who will be staying back?
Will anyone cover the tunnel out or just leave a Swiftwing watching or perhaps a canine to bark and run?
It was suggested that Thoroncir and Gwaelur will be needed for melee and Miron would be on bow and the others seem to be more up in the air.
Let me run and take a look at the tunnel and see if we can’t figure out a way to collapse the entrance while Ghan is casting. It will be one less thing to worry about.
I’ll follow the advance party and find somewhere to lurk within a short bowshot of the tower and the scouts’ intended line of withdrawal, in order to slip in behind the pursuing monster and start to pepper it when the fighting starts; or alternatively to discourage any following goblins and help keep things confused.
Would cutting the bow string on the troll’s crossbow cost Elfstan his invisibility?