Argthtjtr

I have tried looking on the internet and the FAQs but I couldn't find an answer to this.

It seems like when you cast a spell on yourself and spell turning is on it gets reflected to yourself...but you have spell turning on (unless the charges were consumed by your spell) so it should create a resonance field.

This doesn't seem right, but there's no exception on spells cast to yourself in the spell description. The only thing one could say is that the resonance field paragraph says "attacking spellcaster" which implies a hostile action, but I don't really want to imply things and this seems just a case of bad wording

As written, I think it is unclear (bad wording as you say), what is meant to happen and it'll truly be up to the DM to decide. But I'll take a stab at it:

Let's break the spell description down a bit. As per the Spell Turning description:

Spells and spell-like effects targeted on you are turned back upon the original caster.

This DM would rule that Spell Turning would turn the spell back on you, as the description says. Hence, if you target yourself, you are still the target, but you also lose x levels of Spell Turning doing that.

Now, there's the question of the resonance field:

If you and a spellcasting attacker are both warded by spell turning effects in operation, a resonating field is created.

The spell does not, and cannot differentiate between casters (you aren't concentrating on it or anything) and so, as it is written and because the spell doesn't know attacker from non-attacker, there can be a case for the resonance field effect. Definitely--and it could be a very fun, random thing.

However, there is also a good case to be made that since there aren't really two Spell Turnings reacting against one another that this effect wouldn't occur. To this DM, a resonance fields requires this set of events:

1. a spell cast on you by attacking/other spellcaster


2. spell returned to "enemy" by your Spell Turning
   


3. spel returned back to you by the attacking/other spellcaster's Spell Turning
   


4. a resonance field effect is created where you roll for a random effect from the table in the spell description (I picture a spell stuck between two bubbles exploding into a random effect)

Despite RAW, this DM would rule that no resonance field effect would occur (unless the scenario above is met). All of this is to say that once you cast Spell Turning, do not expect to target yourself with spells or else lose Spell Turning levels.

Now, if you cast Spell Turning on yourself while you already have Spell Turning cast on yourself... ;)

You create a resonating field.

Since you are attacking yourself, you are the attacking spellcaster so as it states

If you and a spellcasting attacker are both warded by spell turning effects in operation, a resonating field is created.

If the effect is beneficial (not harmful, as I suppose most spells you want to cast on yourself are), then I'm not sure at all that "You and a spellcasting attacker are both warded [...]" applies.

Therefore, no resonating field should ever be created in this case.

Starting from this assumption, what happens when you try to buff yourself is that the spell bounces on the spellcaster, again and again, until the affected spell levels are completely consumed and the spell has a chance of affecting either its target or its caster.

In short, casting a buff that is susceptible to spell turning upon yourself succeeds, but spell turning ends.