Scenario #4, Lair of the Twisted Summoner

(A short adventure for a party of 1st level characters) 

When Old man Lukus died of old age it was uncertain who should take possession of his farmstead near Threshold. Lukus was a bounty hunter almost up until he died, hunting orcs and goblins. The Threshold town council decided that it should be sold off, with any profits going to the council. Before it is sold, the council ask the PCs to check out the farmhouse to make sure that there is nothing too valuable nor too dangerous in their new acquisition before they sell it on.

Old man Lukus was supposed to have an older brother, but nobody knew the brother's name or where he could be found. He was supposed to have stayed with Lukus for a while ten years ago but nobody noticed him leave or knew where he went to. 

In fact, the brother, Vermix, is still inside the property, or more precisely underneath it. He is a Twisted Summoner and has used his minions to excavate a considerable lair underneath the farm. The stairs down to the dungeon are in the main farmhouse. Visitors to the farm will notice that the herd of 20 sheep are alive and well in their pen - someone has been tending them - Vermix has been keeping them as a supply of food, with the kobolds shepherding the sheep.

1. Entrance hall and guard post: 3 hobgoblins, 2 of whom are controlled by Vermix, the other is not. 
2. Hobgoblin barracks: 4 hobgoblins, 2 of which are under control.  
3. Hobgoblin leader (under Vermix's control, normal 1+1HD, 9hp (max)) + pet giant ferret + treasure sack (1 amber gem worth 100gp, 1200sp, 240gp):
4. Well room, also quarters for 5 kobolds.
5. Storeroom. No monsters, just food
6. Kitchen and dining hall. 4 kobolds + 1 hobgoblin, plus a roasting sheep on a spit.
7. Summoning Room: Large statue of demon with Magic Mouth spell saying in goblinish that Vermix has been chosen to lead them to victory by establishing a mighty fortress here. 
8. Armoury. No monsters but on racks and shelves there are 3 hobogblin/human sized suits of leather armour, 4 shields, 2 swords, 4 kobold daggers & 3 pick-axes
9. Prison: 2 hobgoblins are behind bars with another one guarding them. The prisoners, no longer under Vermix's direct control, are reluctant to accept Vermix's non-magical authority over them. The guarding hobgoblin is not magically controlled either but believes that Vermix is worth following for now. 
10. A pair of enraged gnolls are here. They have not been summoned but charmed, and now the charm person spell has worn off. They have not discovered the secret door on the north wall, and they cannot get over the pit outside the west door. One of them has a pair of bronze and silver bracers on their wrists (worth 40gp each or 90gp as a pair).
    a) This pit is 10' deep and is crudely covered. with dirty grey canvas (breaks if more than 50lb weight applied). Anyone watching out for traps can spot it on 1in 6, while thieves & dwarves looking for traps can spot it on 1-3 in 6. Anyone falling in suffers 1d6 damage. 
11. Vermix's quarters: 4th level Twisted Summoner. AC 6, Mv 120', hp 11, Att 1 dagger for 1d4 or 1 spell, Save MU4, Ml 10, Align C, 125xp
    Str 10, Int 16, Wis 12, Dex 14, Con 9, Cha 10
    Equipment: robes, spellbook, 4 daggers
    Memorised Spells: Charm Person, Magic Missile, Web, Mirror Image 
    Spellbook:  Charm Person, Magic Missile, Read Magic, Detect Magic, Summon Kobold Minion Web, Mirror Image, Summon Chaotic Minion I. 
    Treasure: 400gp, 3500sp, silver & lapis-lazuli amulet worth 200gp, tapestry worth 400gp hanging on wall (showing a battle between an angel and a demon, with armies of Law & Chaos battling in the background).
    There is also a folder of correspondence between Vermix and an apparently senior chaos cultist, which includes mention of other cells in other settlements including Penhaligon, Castellan Keep and Luln. 

Design notes: 

If Vermix is 4th level Twisted Summoner, then he can control 8HD and can use Summon Chaotic Minion I. Although somewhat limited, Vermix could release minions into the dungeon, making them unreliable but more numerous. 
So he has 4 hobgoblins and a hobgoblin leader (1+1 HD but max hp) + 4 kobolds under his direct command. But also 3 hobgoblins and 6 kobolds not under direct control, but who stick around because they are kept in line by the controlled minions and have nowhere else to go.