I have to admit that, when we came face to nose, I did go a bit girly and shriek like Mammy Two Shoes when she sees Jerry the mouse.
It got me thinking about the classic movie scene when the heroes are going through a tunnel or sewer and a horde of rats comes writhing towards them and how whenever I've set the same scene in my game my players never react like I did when I saw the mouse? The D20 SRD says that a rat swarm will cause
"Distraction (Ex): Any living creature that begins its turn with a swarm in its square must succeed on a DC 12 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based."
The problem with this is that I want the players to suffer the effects before they are in the swarm and I want a fear condition not nausea. Fear also escalates with exposure so a character who fails a fear check (Will save) is Shaken, fail twice and they're Frightened, fail three times and they're Panicked. I just want 1 roll so I'm going to try:
- Fail by 1-3: Shaken
- Fail by 4-6: Frightened
- Fail by 7 or more: Panicked