I.e., is exposure of sunlight onto the peripheral vision less damaging than exposure onto the fovea?


Question: Effective game mechanics for handling conflicts with spirits
Answer: The Dresden Files

The fate-powered Dresden Files RPG has very good rules for summoning, containing, and controlling spirits / faeries / ghosts / demons.

Each of those three tasks - summoning, containing, and controlling - is dealt with in sufficient detail to be flavorful, but like most of the dresden-files rules, you can skip the boring parts. 

Is your wizard calling a minor friendly, like Toot-Toot? You can probably get away with a single roll. 

Pulling up something from the wrong side of the Nevernever? A big bad Thing that would pick his teeth with your athame if it weren't for that pesky summoning circle? Oh, and is that a pack of howling ghouls hammering at your door while you chat with this critter? Then you're in for all the rolls and attention that such a dramatic, possibly climactic moment deserves.

Sorcerer

Ron Edwards' Sorcerer is all about summoning, binding, and interacting with demons. I have never played it, but I hope to remedy that soon!