Room 1. Spider webs including a large spider at 1A, some moldy sacks, a garnet in a goblin skull over in the corner (B); it all sets the tone of rot and refuse that permeates the place. That goblin may have been a member of the raiding army that took down the Monastery--or he could have wandered in at any time since. How the garnet got in his head is a curious mystery to consider. Also, please mind the yellow mold (25%).
One other thing of note is the oak door over at 1.C: Moaning can be heard behind it and, if opened, a gust of wind will extinguish all torches. Where did the wind come from? Sure, there's a subterranean stream running through the adjacent room--typically a great venue for creating air movement in a cavern, except that the stream "fills entirely" the tunnel through which it both enters and exits the room. Which is to say, there's no room for any air movement, much less wind forcible enough to extinguish all torches.
Those brave enough to enter the dark, windy cavern will find:
Room 2. WATER ROOM: Although the room is described as holding only "8 rotting barrels" (over at location A) from the hoard of casks and barrels which were once stored there, several of the barrels in the room "hold water" as they were "new and being soaked to make them tight" at the time of the downfall. This might give a sense of the passage of time to those familiar with the decay rate of wooden barrels.
2.B: The limed-over skeleton of the Abbot lies at the bottom of the stream that passes through the chamber. His corpse has undergone a "sea change," a reference, as the ensuing narrative example of play points out, to Shakespeare's Tempest:
Full fathom five thy father lies:
Of his bones are coral made:
Those are pearls that were his eyes:
Nothing of him that doth fade
But doth suffer a sea-change
Into something rich and strange.
Amidst the remains of the abbot the attentive adventurer will find a scroll tube and a key. Acquiring these items is not a sure thing as Characters who dislodge the scroll tube have to make a successful "to hit" roll as if hitting AC 4 in order to successfully grab the scroll before the current of the stream takes it down stream beyond return. Is this a nascent action resolution system using "to hit" as a means of determining success at non-combat actions? Sort of a proto-SIEGE engine for you C&C fans?
Inside the scroll tube is a map of the underground portion of the monastery, but it is almost entirely smudged beyond use; showing only the two areas that the PCs will already have seen by the time they find this map along with an 80' section of hall in the "crypt area" to the south with "miniature sarcophagi" depicted in it. Not super helpful, but it will definitely aid parties in finding the crypt area which is accessible only via the elevated secret door in room 3. (Or the stairs at are 39).
The key in the abbots calcified hand allows the secret door in room 28 to open toward the "treasure room" (29) rather than to the stairs (30) down to the caverns, which is, presumably, the default. Is this where the fabled fire opal can be found?
Of significance here is that the abbot's body is a) located where it would easily be found if it were still encased in flesh, and b) still in possession of the ring and scroll case. Presumably anyone who had reason to seek the Abbot out--such as would be the case if the besiegers were either politically motivated or looking for the fire opal in his possession--would have searched every corpse to find him; either to make an example of him by trying him posthumously and impaling his corpse on a stake for all to see, or searching his carcass for the gem or some clue as to its whereabouts--like, say, a key or a map. That his body is lying in what would have been plain sight at the time of the siege and yet retains these two possessions indicates that the marauders were probably neither aware of the fire opal nor concerned with the political significance the abbot's corpse. Rather, the raiders who took down the monastery were more likely foreigners looking for obvious treasure; much like the first Vikings who raided the Monastery of St. Cuthbert* at Lindisfarne in 8th century Britain. Whoever these dudes were, they were in it for a quick score; snatching gaudy, jewel-encrusted religious implements, potential slaves, and casks of wine and beer would have been their prime interest. Rifling the pockets of an ascetic monk probably didn't rank too high on their to-do list.
*Yes, I did intentionally reference the real St. Cuthbert as a not-so-subtle nod to T1 Village of Hommlet and its sequel T2 Temple of Elemental Evil. This place is a religious edifice sacked by an army years ago, now an unholy ground inhabited by lowlifes, critters, and the undead; doesn't it maybe seem like it might have been an early version of the Temple of Elemental Evil? Sure, pretty much every dungeon had a background that sounded a lot like that back in the day, but considering that the DMG was published around the same time as T1... maybe this is what T2 might have looked like before it spent the next 6 years simmering on the back burner.
Next up: Room 3 and the Wandering Monster Tables