Very interesting points Bill. I hadn't even thought of the repercussions of additional magic, and I'm allowing players to use everything in both Channeler and Seer [so the spell list is already larger]. It also means alot less double checking between "do I know this spell or not". Originally the intention was that they couldn't resist spells of a higher level then they could cast [hence the "spells you can cast"], and I'd like to keep that I think.
Good point, I hadn't considered the inability to resist spells of a higher level. You could tie it to their own level of Circle of Power.
Arcane Bulwark: At level 4 choose a number of Schools of Magic equal to your starting action dice. You gain Spell Defence <value> against spells from these schools and whose level does not exceed your own Circle of Power rating. At level 8 this increases to Spell Defense <value>.
Probably need a better wording, but the idea is there.
I agree the wording should be changed to reflect that its a choice.
Note: Changed Core Ability and Spell Defence in original post, cleared up wording of Arcane Reflection.
Hows it look now?
Theoretically, someone could have Enlightened Resolve, so their max ranks in resolve would be Career Level +5. At level 10, using 15 + Resolve ranks, that would equate to a Spell Defense of 30 (28 without Enlightened Resolve). At level 14, the second part of the ability kicks in, as well as 4 more ranks in Resolve so now the Spell Defense is 39 (37 without Enlightened Resolve).
At level 10, a dedicated spell caster could reasonably have a Spellcasting of 15-20 (13 ranks + Int + some miscellaneous bonus like Arcane Might). At level 14 we are looking at Spellcasting of 20-25 (another 4 ranks and maybe an Int boost).
At level 10, the caster would need a roll of 8-15 on the die to get past spell defense and at level 14 this would jump to needing a 12-19 on the die.
This seems reasonable. The earliest they could get Arcane Bulwark, they would have little over 1 chance in 4 of avoiding spells targeting them, 4 of 8 schools are covered and a little over half that qualify would be defended against, and dedicated Hierophants become hard to cast against, and downright dangerous once they get their game breaker.
If you make the base 10 + Resolve and get rid of the +5 at level 8, a 10th level caster now only needs to roll in the vicinity of 3-10 on the die. Since the Spell Defense is hard capped by ranks it will only ever increase 1 per level, whereas the Spellcasting can increase at an increased rate (from further Int gains and possibly Skill Master feats from a Spider Nation Caster). As you approach level 20, the required die roll is going to get even less, so 10 + Resolve seems too low to me, especially since it only works on a subset (only targeting him) of a subset (belonging to specific schools) of a possible subset (only those of a certain level or lower) of spells.
Adding to that is that this class' game breaker is to turn spells against their caster that are successfully defended against, so it is important that this Spell Defense actually works. Otherwise, you may end up with a class that specializes in fighting "corrupted, magic-infused beings of chaos and madness" while said beings can easily shrug off and laugh at what should be your most potent ability.
Something else I thought of after my earlier comments, but one thing to bear in mind about using action dice for number of schools of magic is it IS possible for maximum action dice to GO DOWN after the ability is granted. For instance, a Dwarven Keeper 4 / Mage 4 / Thaumaturgic Hierophant 4 who decided to, for whatever reason, take Mage 5. Mage, a base class, now being a higher level than Keeper, an iconic class, would mean the dwarf would receive 2 fewer starting action dice. In the rare event this happened, I would treat it just like losing spells known where they lose access to certain schools and regain them when the action dice go back up, but they must first choose schools that were previously lost.