When you're trying to figure out how to get triggers to do things, I really recommend Rumble's Trigger of the Day posts. They're examples of how to trigger many interesting things.
I especially recommend this one:
tbamud.com/forum/3-building/3800-trigger...rrelled-shotgun#4791
Yes, I realize that isn't a spell but the thing about the triggers that he's chosen is they're usually flexible and can be modified to do different things. In fact, modifying them is a good thing since it's good practice in finding out how triggers work. Some of my best triggers have been modified from other triggers.
