Continued from here.
Baron Gusorio finished off another cup of the fine mead. He sat quiet for a moment, gathering his thoughts. His rapt audience waited patiently for the gray haired man to continue with his rambling advice. Already, thoughts were spinning through their heads of the great adventures they would have.
Lord Gusorio finally continued. "I told you about how we rescued Shalea and then had to get her werewolf curse removed. Another time, we'd found a fountain in the dungeon--on the third or fourth level, I believe--that could cure diseases. It was hard to get to, though. There were lots of slimes and molds in the area, and creatures that fed off of those disgusting lowest forms of life. Well, after we ran into a pair of mummies on the sixth level, Vertosh the Dwarf and I had caught the mummy rot. We hauled out all the good treasures from the mummy tomb, gave the others a bit of time to rest and heal up, then set off again to find that pool so we could get rid of our affliction...
I think most DMs and module writers have a lot of fun with the 'special' encounters within a dungeon. They're the oddities, curiosities, magical zones, and weird stuff that tends to be fairly memorable. Unlike 'orc encounter #38" a room with howling winds from nowhere and a narrow bridge over a lava pit tends to stick in your mind. They're sometimes challenging, sometimes bizarre, and sometimes useful.
Often they're just discovered randomly, during exploration (scouting), or they're searched out after learning that they might exist (fact-finding). But once they're known, and properties of them assessed, they can become useful tools for a party of adventurers.
Like in my example above, curative sites or magical 'buffing' sites can be worth visiting over and over again. Making a small sacrifice at a shrine to a battle deity might result in a free Bless spell before tackling a dragon or other big monster. A pool that turns the bather invisible might also be a favorite spot to visit. There could be a machine (or monster?) that takes in coinage and spits out gems of equal value, making treasure easier to carry. These sorts of specials are most useful if visited as part of another type of expedition.
But there are times when the 'special' might be worth going to all of itself. Portals to distant lands or other planes may lie within the dungeon. A monstrous sage (gold dragons, hsiao, djinn, etc.) may lair within the dungeon, and the party may need to seek out that sage's wisdom. Perhaps a character has a curse that can only be removed at a specific special location within the dungeon.
If the former, characters will want to prepare for the expedition based on their primary type of expedition. If visiting that invisibility pool while scouting, leather armor and utility spells are likely best. But if getting invisible as a way to surprise the Frost Giant Ysgeir and ensure a free round to 'soften him up' then it should be plate armor, fire balls, and all that jazz.
In the later case, getting to the 'special' and then home again is the objective, so only what equipment known to be necessary to reach that area should be brought, and the party will likely not need to bring along lots of men-at-arms or the like. The Fighters may be armored up in case of surprises, and the spell-casters may want a variety of spells, as those annoying random encounters are likely to be the only battles fought (assuming the party has scouted the area well enough to avoid any new monsters that may have moved in since they discovered the area). But the expedition will likely tend to be a short one.