Last session we had questions come up with Protection from Evil. Looking at the spell, it's pretty straightforward, but nonetheless questions came up.
What does the DR protect against? It's the Armor spell with a limitation to only affect attacks from evil, basically. So direct attacks of all kinds from things marked Truly Evil (only), including weapons and ranged attacks. It does not affect indirect attacks, like explosions from exploding Doomchildren or shrapnel from the same, or falling damage when they knock you down from your Walk on Air spell, or fire damage when you catch on fire from their spells.
The DR stacks on top of all other DR, right? No. The DR stacks like normal Armor spell DR - so you take the higher of Fortify or Armor, not both. Sorry, no +3 from Armor and then +6 from Protection from Evil.
What does the Magic Resistance work against? Spells. This is not +2 Resistant to Evil Supernatural Powers per level. It's +2 Magic Resistance, per the spell.
Plenty of Truly Evil foes have abilities that are neither physical attacks nor spells, per se. This does not help against them. That might seem a bit unfair, but it's a cheap spell for what you get. and it's very specific what it gives you.
I'll use this page to list any other ruling that matter on the spell.