Tips for making a mirror universe setting?

[Cybris75]

It's my turn to DM soon, and I need to pick up some unusual stuff from the last time by having a portal to some sort of mirror plane, where the stuff we don't have in our custom setting (e.g. psionics, gunpowder) replaces commonplace stuff (in this case, magic and bows).

I've already decided on making orcs the flexible, civilized and numerous race. Humans are always chaotic evil. The evil princess has kidnapped a beautiful dragon. Magic is unknown, psionics is commonplace. There are lots of psionic dragons, but they are quite weak. Mindflayers are nice, wise and helpful. Drow are a noble race, other elves are barbaric tyrannical slavers. The self-sacrificing duergar psions barely can keep the dwarf threat at bay. The tricky trap-laying gnomes want to eat the kobold's babies, but the mighty kobold paladins and inquisitors see through their illusions.

I still have to decide about what to do with the gods (we use Greyhawk deities).

What else could I do to the setting to make it different, shocking, but still believable? I don't want it all to be a bad joke, more like a "what if..."

Also, which plot points can I use to turn the expected into the unexpected, e.g. reverse common tropes? I'm still at a loss about what sidequests I can put there for the PCs.

The main quest is for a McGuffin the PCs have to retrieve and return to their world in order to seal the gate with.

Edit: this is partially a sanity check for our banlist. We usually don't ban stuff because of power level, but because it doesn't fit our setting. Hence putting psionic, gunpowder, dinosaurs, etc. in there.

Edit2: if it helps, this place was created by a powerful epic chaos dragon that likes to mix stuff up and rip holes in our normal setting sometimes.

[AuraTwilight]

I still have to decide about what to do with the gods (we use Greyhawk deities).

The compassionate Demon Lords forged the Material Plane generously out of their own Abyss, not desiring worship but only the well-being of their new children, and then the malicious, greedy Gods showed up and began demanding worship or obedience under penalty of smiting, remaking the world in their own image. The Demon Lords weep for the suffering of their creations and vowed to always oppose the gods, offering their faithfuls a happy afterlife in Hell, where all worldly pleasures exist.

[Qc Storm]

All innkeepers are friendly beholders.

[Crake]

All innkeepers are friendly beholders.

happens more often in a normal setting than you'd think

[Seffbasilisk]

Widely acknowledged Halfling Judicaries have stations in a network that communicates via a set pattern of flags. Locals come to have them recite local laws and precedent. Their barristers are said to be sublimely detail oriented.


Mercenary Githerazi sell their silver swords as bane against planar exploration.

Giants study the cycles of life, and maintain several massive library/planetarium research centers, trying to better equip future generations.

[AuraTwilight]

Kender aren't the slightest bit annoying and everyone loves to be around them.

[Segev]

Given the things already in place, I would go with "light" being associated with evil and fear. The light-bringing humans and elves blind the noble orcs and show their dominance over the civilized caverns by lighting them up. Sure, orcs and drow use light sources placed at strategic locations so they can watch areas beyond their Darkvision, but the embrace of safe darkness, the comforting lack of harsh color, is a good thing. Instead of "fear of the dark," it is common for kids to be afraid of light. It's associated with fire and hateful magics; like many things, it still is useful in controlled amounts (even in normal settings, darkness is the friend of rogues and those who sleep), but it's not something that is trusted. Things lurk or menace in the light.

The surface world is where the evil races were banished; the comforting dark, the rich farms (of fungus) are deep below. Bathing things in sunlight makes them fill with bright, vile power in profane rituals. While the Underdark has poisons just as plentiful as in standard settings, the civilized races don't cultivate them any more than surface ones do in standard settings. Likewise, the "brightly colored == poison" thing of real-world nature is garishly true in the popular mindset of this mirror world of yours. Poisonous things grow in the light. (Think jungles, with their reputation for poisonous vermin and plants. Now make the gardens cultivate that alongside food for the villainous surface races.)

Again, light is scary and dark is comforting, so the feeling is that the surface-dwellers are trying to invade and take over these things. That they always retreat back into the light is as much as sign of their evil as the fact that standard-setting evil races retreat into the darkness. Heroic orc and drow adventurers venture into the bright day, fighting their way up and doing Tower Climbs (instead of Dungeon Crawls).

You will need to pay particular attention to your "wise and kind" illithids. Mind Flayers are amongst the single hardest races to make non-evil. Even vampires can pull it off better; they can survive on less-than-lethal blood-drinking, while mind flayers eat...brains. Of sentient creatures.

Perhaps the Illithids are much rarer; more common are Neothelids and Larval Flayers, which are kept as pets and the like. The Elder Brains are in deep communion with the natural world of the caverns in which these ancient and wise settlements are established. Only terrible criminals sentenced to die undergo the standard-setting "traditional" Cerebromorphosis, and those Illithids who are born from it are often dedicated to righting the wrongs of the being who gave them life.

Mind Flayers are, however, also the druids of the setting. Perhaps a psi-druid, or perhaps one of the few places divine magic still is "common," these mysterious keepers of ancient lore and the natural world of the underdark actually have ritual sacrifice of orc, drow, and other local sentient beings for their meals. These sacrifices are an honor, and are actually performed with extensive magical backing: the Illithids have extensively improved their ability to get "flashes" from those whose brains they consume, and share that knowledge with the whole community. Meanwhile, Reincarnation is used on the sacrifice, because they're not murderers. But this is another reason actual Illithids are rare: they never want to actually be a burden on the people who live with them.

Cerebromorphosis is also performed on revered and wise elders who have their minds constantly read throughout the process, so that the Elder Brain and the newborn Illithid will be able to shape a symbiotic relationship such that this new Illithid will have, effectively, a mental presence of the elder to serve as his advisor. Such illithids consider themselves blessed for not being born of criminals, and dedicate themselves to using their honored host's wisdom for the betterment of all.