Concept: Lucid dreaming
Tested in: The Great Tower of Oldechi
What it is: D&D likes working via cause and effect. Orcs don’t lose hit points at random, they lose hit points when they get hit by hammers. Wounds don’t heal except when treated by magic, medicine, or time, no matter how much a player might prefer that their character had taken no damage. Spontaneous, unexplained occurrences live solely in the realm of flavor, and even then they sometimes have rational explanations, like a thick fog covering the besieged village because a druid is keeping it there. And while a DM can get away with the occasional illogical act, players don’t have the same leeway. Their actions should always make some sort of sense.
But Floor 27 of the Great Tower ran entirely on random occurrences. It was so random, I don’t even have notes for it, except at some point I think the party fought Tiamat. Everything was generated live at the table, and the players eventually learned that it was because the entire floor was mutable. Once they figured that out, they wanted to take advantage of it.
Using a technique I adapted from the Dresden Files RPG, I let them affect the floor by rolling three simultaneous checks. Basically, they could declare anything they wanted and it would happen. But their Intelligence check would determine the result of their declaration, their Wisdom check would determine its severity, and a Charisma check would determine its form. For example, a player might say “a wave of lava surges over the people chasing us and buries them”. Good results on all their rolls would cause exactly that, no further justification needed. A bad Intelligence check would have a bad result (the lava does not bury the enemies, but instead lights them on fire so they deal extra damage), a bad Wisdom check would have the opposite severity (the lava doesn’t “surge” as much as “trickle”, creating maybe one square of difficult terrain), and a bad Charisma check would have a different form (the wave is actually a crowd of people doing the wave, holding back the enemies with a mass of bodies; not functionally different, but weirder, and it might lead to other applications later).
What I wanted: Characters flexing their god-like power against the full brunt of everything I can throw at them. The players would have a lot of fun playing with it, especially when they fail and they get to deal with the consequences of badly-worded or poorly-phrased declarations, and they would use their power to figure out they’re in a shared lucid dream and wake up so they can progress to the next floor.
How it went: Exactly as expected, pretty much to the letter. The players quickly went wacky with their declarations and I went wacky with the failures. I don’t remember everything, but I do remember a player conjuring a Godzilla-like monster to destroy a city, and failing such that he instead got a swarm of chicken-sized Godzillas whose collective mass was roughly the size of the original. It was full-on collaborative storytelling, a welcome breather floor after the group murdered most of another party in a post-apocalyptic wasteland and before they had to break out of a prison guarded by an immortal mind-controller.
What I learned: Players like having power, even nearly-inconsequential power in small bursts with high limitations. It was experiences like this that convinced me it would be fine to give my players wishes. If I did this again, I don’t think I’d change anything, except maybe giving the party an enemy with the same powers but more experience in using them.