So, I'm creating a city for an Oriental Advertures setting ... The city is really just a small town, hidden in the mountains from most people. The small town surrounds an extremely large training facility. Now, my character (I'm creating the city for the DM and I asked him if I could include monsters and such in certain areas) has returned to the compound with his fellow adventurers to find out that it has been abandoned. On further inspection, the compound has been overrun by the undead; I've come up with using several doc cu'o'c and stuff, but I'd like help with it.
We're able to use the Monster Manual and the Oriental Adventures book's monsters, so give me an idea ... I'd like to find a monster that has a challenge rating of 2 or less so I can throw a LOT of them in one section to freak the kids out (we're level 3 at the moment, but the other players are VERY inexperienced, so a LOT of monsters will surprise and intimidate them).