Spell Effects in the Dungeon looking at the spells in Men & Magic as spells that had been cast well in advance of player characters coming down through a dungeon. In this follow-up I will be looking at the spells from Supplement I: Greyhawk and their potential impact on a dungeon.
One note is that Greyhawk has Permanent Spell, so I'm disregarding the duration limits for these spells. Assume that the magic-user is either an archmage, or has scrolls or other access to Permanent Spell. Note that this is a general improvement for having spells pre-cast in the dungeon.
Darkness, 5' Radius. Make one square of 10' map into absolute darkness. Great for setting the mood or hiding a devious trap. Or create the apparently infinite pit trap: Darkness and Silence at the bottom of a 10' pit. People fall in and you can neither hear nor see them.
Web. Nothing like a big sticky mess for characters to wade into. Very good for lining pit traps, the bottom of a chute, or in front of the lair of a monster.
Magic Mouth. There's a lot of potential for these. Greyhawk lists the possibility of using them attuned to alignment, or specific individuals. This makes them excellent alarms, but they're also good if you want to give a riddle, a joke or invoke a trap. For instance, consider a Magic Mouth rigged to deliver the command word to a wand of Fireball - a perfect explosion trap. The structure of the spell gives a perfect excuse why dungeon denizens don't set off the trap, too. Of course, this can be used on other kinds of wand to make different traps.
Pyrotechnics. The fireworks variant is good if you combine it with the Magic Mouth wand trick detailed above. A permanent smoke effect can create a nice low-visibility area for a trick or trap, or a fake "dragon" lair that will freak a low-level party out.
Explosive Runes. Well, this one is pretty obvious. BOOM!
Rope Trick. A rope ascends upward and disappears into another dimension. Pulling it will bring whatever is at the top of the rope down on the characters. My personal inclination is to stick a bear or two up there, but it can be pretty much anything you'd like to have inquisitive PCs bring down on their own heads.
Suggestion. You can pretty much have an otherwise intelligent character doing anything the magic-user would like. It's prime for just plain weird encounters – why is that guy carrying a bucket of acid back and forth? The wizard told him to.
Ice Storm. If you are using 10' squares, in a dungeon, the ice storm can impact 27 squares - a big swath of the dungeon. If temperatures cooperate, this will let you create a frozen sub-environment with slick floors, icy hailstones, and/or snow - or with permanency, a perpetual ice storm. If is too warm, you can wind up flooding the same area.
Repulsion. Creative casting can make a room, area or object unapproachable in a spectacular way. Most interesting if PCs try using missile weapons on it.
Delayed Blast Fireball. BOOM!
Reverse Gravity. It's pretty obvious what you need to do here. Three 10' cubes have reverse gravity and characters entering them fall upward. Very interesting in a room where only part of this is true. Extra fun bonus: make the ceilings more than 10' high.
Charm Plants. The spell description says explicitly that it's a good warning system. Not to mention things like strangulation ivy.
Mass Invisibility. What's better: six invisible dragons or a small invisible army (300 men plus horses)? Either way this packs some punch.
Symbol. This is of course made to go into the dungeon. The Death symbol is pretty much concentrated havoc, though others such as Discord have roleplaying potential.
Polymorph Any Object. This spell pretty much lets you make anything you want.
Time Stop. Using this as a trap may cause some very interesting philosophical debate. If you want to make creative solutions necessary instead of a Dispel Magic, stick the nastiest monster you can find in the affected area.
Prismatic Wall. When you really need to stop someone from getting in.
Now, I could go and list the Limited Wish and Wish spells - but they pretty much would let you do anything you want. That's endlessly creative but has no specific ramifications to look at. Overall I thin the Greyhawk spells have a lot to contribute to the dungeon by having them cast in advance of PCs arriving.
On reading your comments on Reverse Gravity, I immediately envisioned a room with a high, domed ceiling... with reverse gravity affecting everything but a small circle in the center. PCs step in, fall up, slide "down" the dome to the center of the ceiling, fall back to the floor - and are trapped in the middle of the room until they can think of a creative way to get out! Also easy to give imaginative hints for: a small pile of rubbish in the center of the floor, the double squeak of a rat getting flung up and back down, etc.
Put a inward sloping spike in the middle under the center of the dome and it becomes a death trap, they are either impaled or miss the point and are slid back out to the inverse gravity bit for a repeat. ;-)Delete