Dungeon 23, Room 1.3

Room 1.3: This is inside the base of the Northern Barbican Gatehouse. When the barbican was originally built, this base was a solid rock foundation, in-filled with stone debris and aggregate. It was still intact when the castle was defeated by sorcery and treachery, but in the years since, it has been consumed by the acidic roots of several semi-intelligent plant monsters. Their digestion has weakened the tower, causing the floors above to partially collapse, and leaving a hollow that has of late become a nest for a large colony of bats.

The locations marked A and B in this room are holes leading further below, opening onto the sublevel areas 2.XX. The holes appear to be ringed with snarls of thorny roots. These are two Stone Creepers (2x CR 1 medium plants from the Tome of Beasts 2).

In addition to the two Stone Creepers, a total of 7 Swarms of Bats nest here. (7x CR 1/4, Monster Manual)  During daylight hours, assume 1 swarm adjacent to each of Creepers A and B, and the remaining 5 Swarms in the larger cave marked 1.3C.  At sunset, the bats alight and fly out of the tower. They return 1 Swarm at a time over the hours before dawn. 

Lastly, the dark cave here is also appealing to snakes, of which there are many in the vicinity of the castle. At any given time there are 1d4-2 Poisonous Snakes (CR 1/8, Monster Manual) here, either hunting bats, or curled up in the roots of a Stone Creeper.

 

A Potential Disaster: Nothing that lives in this hole will seek to cause trouble for the PCs, but incautious PCs who plunge into the depths, make shocking loud noises, or unleash open flames will create a chaotic and perilous situation. 

Stone Creepers are not generally aggressive to other organic life, but they will get panicked if the PCs try to uproot them, or if Medium size or larger PCs try to push through or past them to get to the area on floor 2, below, and will use their acid-exuding thorns to defend themselves in such circumstances. If the PCs bring open flame down in to this area, the Stone Creeper's panicked reaction will be even worse. 

The wall marked 1.3D has been weakened over the years, and the creature will rip its way through to escape. This will cause the entire west tower of the north barbican gatehouse to collapse. Damage to any PCs in or within 10 feet of the tower (and any Sword Wraiths in 1.2, above) is as described for the Stone Creeper's Weaken Stone ability. If the Bat Swarms and/or Poisonous Snakes survive they will become agitated and violent. 

In the wake of the collapse, a large pit will be left open directly into area 2.XX. This collapse will obviously raise a great commotion, and the sudden unexplained transformation of the tower will put all the denizens of the ruins on edge. If this happens, raise all Alert Levels by 1.