Mostly huge, garishly colored slimy monsters have overrun the Eastmarch. Refugees are crowding into the city, and a large refugee camp by the north wall has been set up. The Temple of Osiris is advertising for adventurers.
The monsters are all different. Even the occasionally recognizable monster is the wrong color, and they're mostly very underpowered. One refugee has been celebrated as a "Dragon Slayer", since he took out a huge, firebreathing beast with one blow of his yard rake. The tale definitely grew in the telling, but the man, "Lucky" Luke Sty-walker, former pig rancher, hasn't let it go to his head. After all, after he killed the "Dragon", a giant slug ate his house.
On the other hand, there was the "killer bunny", that killed 6 sheepdogs and a wolf one night, right in the middle of town! It would have probably continued the rampage, except that it started to melt at sunrise (a Rarebit of luck, that.)
Finding the source of these monsters is the quest, obviously, and this is not too difficult a task, as long as the adventurers don't get eaten. Nearly every monster has left a clear and obvious trail. The trails all converge on a stream bed. Near the headwater of the stream is a cave mouth. An idiot ogre couldn't miss the fact that major traffic has issued from it. Inside the cave mouth is a very standard set of caves, caverns and corridors, unique only in the fact that all of the normally expected cave denizens are absent from, or dead in, their lairs. One exception; the first side cave from the entrance has a very dead 12' cavebear, and a very cute, and hungry, cavebear cub (about 60 pounds). the cub is likely to attach itself to the first adventurer that doesn't hurt it. Like most Ursines, it is omnivorous. Monsters issue from the cave at about 5 per night (2d4/night), and come into being at the narrow end of the large cavern. Some don't even survive walking the length of the room, which provides the heartier monsters with a much needed snack. None of the monsters can eat anything terrestrial. Well, they can chew and swallow, but not derive sustenance.
During the 12 phases of the creation, a light can be seen coming from "somewhere else". Careful attention will reveal that this `light' seems to be coming from a desk lamp. Also visible is a desk with a hunched- over "dwarf" in outlandish garb (actually, it's a kid in a striped T- shirt). Anyone stepping into the circle of light will be transported into a 12'x15' basement room filled with strange and wonderous objects, most of which will not function properly if brought back to the "real world". On the desk are the kid's `lucky dice', which are powerful magic items, and radiate magic strongly (noticed on 11-, 8- by spellcasters). These dice create monsters if rolled 12 times. The monsters appear in whichever universe the dice are NOT in. the Dice can be easily destroyed in either plane, but that destruction will close the trans-dimensional door that is in the basement behind the desk (which is also obvious to most adventurers.) While the door is open, anyone leaving the room will be transported to their own world. Also, magic and technology both work in the basement room only (and in the cave).