Can a warpriest use his fervor ability to cast spells that have no targets? Here is the relevant text:
As a swift action, a warpriest can expend one use of this ability to cast any one warpriest spell he has prepared with a casting time of 1 round or shorter. When cast in this way, the spell can target only the warpriest, even if it could normally affect other or multiple targets. Spells cast in this way ignore somatic components and do not provoke attacks of opportunity. The warpriest does not need to have a free hand to cast a spell in this way.
Clearly this disallows casting hold person on an enemy or bull's strength on an ally. But what about spells that have no "target" entry but instead have an "effect"? For example:
- Can a warpriest use fervor to conjure an obscuring mist?
- Can a warpriest use fervor to cast a summon monster spell?
- Can a warpriest use fervor to cast flame strike on an area of his choice?
1. No. Area effects wouldn't be valid options, especially if they can affect other targets.
2. I technically don't see why not, and since Warpriests are only 2/3 spellcasters, it's not broken to allow it, especially in the endgame. However, I can assure you that it is most likely not RAI, and based on the current text, the assumption is that the spell must target the Warpriest. I'd talk to your GM, but don't be surprised if he says no.
3. See #1. If the spell affects targets other than the Warpriest, then it can't be used with Fervor. Summon Monster gets a pass because it doesn't target anything, but the question then becomes if it's even a valid spell to use with Fervor, which it may not be.
As an added bonus, I don't even think you could use Fervor to cast spells like Greater Magic Weapon (like you need it as a Warpriest anyway), since those spells target the weapon, and not the Warpriest, which is the condition required for Fervor to be applicable.
Honestly I would assume that none of those effects work, as none of them can legally target him (obscuring mist has no target at all, summon monster targets a space, and flame strike targets an area). I believe this is mostly meant to mirror the paladin's ability to lay on hands himself as a swift action, except this works best with self-targeting spells instead so you can give yourself a boost without losing a chance to move and/or attack (for example, allowing you to use hedging weapons to both summon and throw a weapon in the same turn, cast two cure spells in the same action, cast effortless armor so you can charge an enemy that you'd normally be unable to reach).