Motorskills
Explorer
For those wanting to add a little whimsy, RPGnet is compiling a list of 1000 vaguely interesting things you could find in a Dungeon.
Easily tweaked for an Abyss campaign.
Easily tweaked for an Abyss campaign.

Like I suggested back when, perhaps someone has reached this stage of the adventure now that a few months have passed!I'm finding the description of how the Maze Engine works very confusing. It could be interpreted that you roll on the Maze Engine Effects table 1 time, 2 times, 12 times, or 13 times.
The best I can guess, you only roll once (on round 12), unless the party does something to stop it from falling into the lava, in which case you roll repeatedly. It's pretty unclear, though.
Now that I've restarted the thread, I can add that you can find A LOT on this in various realmslore.Also, I've been thinking alot about EXITS from the Underdark. The module basically says to let the characters out after they've discovered that demon lords are infesting the underworld, but does not give actual exit points. I'd like to offer some choices and excitement with the actual escape besides the obligatory drow fight.
Just to report back that this worked like a charm.On the subject of "only 1-2 random encounters a day?" I'm toying with the following idea:
Require a save DC 10 to gain the benefits of a long rest. Failure means all that time was "wasted" (counting only as a short rest). You still can't long rest more than once a day. What save? I would allow players to choose themselves, given a reasonable rationale. (Con and Wis are the givens; Int: "I sleep in a clever area"; Cha: "I persuade Mr Beefcake into letting me use him as a pillow"; and so on). The point isn't to make this an exceptionally hard save to make; but to put the fear into the players since the long rest is no longer a certainty.
I was a bit wary reading the comments about the looseness and lack of detail, but it's actually a complete boon. I have spend a lovely Sunday evening building random encounters: terrain + creature + couple of minutes thinking how the two would play together: Here's my (updated) list so far for the first 22 days. Almost totally based on the dice where they fell. I recommend everyone to give it a try.
I've prerolled the lost levels based on a decent survuval level (+3) which adds significant time.