The only way the basilisks can become wandering mosnters is if they break out of the sealed area they are confined in. The fact that this might happen does not change the fact that, as keyed in the module, the basilisks are sealed into an area. The module even goes into length describing the recently constructed brick walls used to keep them in, and the recent patching that has been applied to them.
Page 4:
"
Ruin Encounter Table (roll d6)
Encounter occurs 1 in 6 (d6), check each turn.
. . .
3. 1-2 Basilisks
. . ."
"* Remove the appropriate number of basilisks from encounter area
#10, temple level."
There is no explanation of whether they "break out of the sealed area" (#10) or not, but they somehow can be encountered outside their "den". And this fact (that they can be encountered randomly in the complex) is, to me, poor design.
(The troll in the box is there because of a stone of diminution, and is likely assumed to be there because there is almost no way for the party to approach that particular chamber without alerting the inhabitants, giving them time to prepare).
"Is likely assumed" is a (legitimate) interpretation, but it is not mentioned by the text. The text tells what spells the cleric will cast if alerted "through loud noise, etc." that the PCs are coming (
silence, prayer, resist fire, protection from good), but there's no mention as to how the troll got in the poor box (diminutized), or why it's there. It just bursts out two rounds after the party enters the room (while they ae probably engaged in battle with the half-orcs). (There's no mention of whether the orcs and cleric even know it is there.) It's a neat trick/gimmick to surprise the PCs, sure, but it just doesn't make any sense -- it's just thrown in without explanation or connection.
And how did those 3 half-orc fighters, the cleric, the assassin, the troll, and the 10 chained prisoners get into that room, anyway? Down the hall past the
glyph of warding (they'd all, including the slaves, have to speak the name of the glyph to get past without setting it off), or up through the trap door (which is literally trapped, and can't be disarmed from below) from the sewage-filled aspis grub hatchery or the net-trapped and strongly defended aspis main chamber?
When I ran this adventure, I had a basilisk come up as a wandering encounter. I ignored that, because it made no sense for the basilisk to be where the encounter happened (really, makes no sense outside their "den", at all).
And when the PCs overcame the half-orcs, cleric, assassin, and troll, they questioned the slaves about how to get around in the complex. I said the slaves were in too bad a shape and too scared to relate anything useful, because even *I*, the DM, with the map of the complex couldn't figure out how they got around in the complex.
This is just two of the problems I see with
Slave Pits of the Undercity. There are more. And its the sum total of the problems that makes me call A1 a poorly designed module. I love the concept, and like I said, I made a whole campaign based on the concept.
Now, you may not see these items as problematic. Great for you -- you may be a very creative DM to work around these things. I, however, 20+ years ago, could not. And I would not try now without working this module over heavily to mold it into some form of sense.
Quasqueton