That was me. So if did, how would I work out the grapple modifier?
Snip...Questions
The answer to all of the questions about the modifier is that they are keyed to the caster of the spell, and not the archer shooting the arrows (if he isn't the one casting).
And the cost for a spell storing arrow is only 160gp, not 400.
How are you getting that math? Spellstoring Arrows are automatically +2, which is 8,000gp, plus the cost of 50 masterwork arrows (302.5gp). 8,302.5/50=166.05...
Wait...what the hell did I divide by that came out to 400? I must be smoking crack today. Sorry for the misinformation.
I do stand by my point, though. If the average fight is 3 rounds, and you're dropping 6 arrows/round, that's 2988.9gp per fight. It's not as bad as I initially thought, since average treasure for a 20th level encounter is 80,000gp (or 20,000gp/person in group of 4), it's only about 15% of your share. It's probably less severe than a wand-happy caster or a potion using fighter, or whatever, though, so maybe it's not so big a deal.
Spells can be cast in down time=free.
If my spellcaster get's downtime and he's got extra spell slots, he's spending them casting things like Fabricate to make money. But, even so, he's keeping up all his defensive/attack spells he usually keeps up, cause I'm paranoid like that. (Or am I the only one that has a DM that will throw 'surprises' at you like that?)
Also, as far as (over)powerfulness goes, compair it to a bane arrow (same cost)
+2 to hit and +9 damage is awesome. Most damageing spells in a spell storing arrow won't be that good.
The utility would be nice thou with Earthbind and Kelp strand etc.
Something that grappled, stunned, entangled, fatigued, exhausted, drained, or hit some other aspect of the character could be much much much worse than the +9 damage would ever be. You successfully nauseate a spellcaster, and he's out of the fight. You successfully fatigue or entangle a charger, and he's doing 1/10th the damage he would otherwise. You hit someone's low attribute with enough to drop them to 0, and they go helpless.
Besides, a gish or spellcaster in the group is going to have the caster level to put much more than 2d6 damage dice in that arrow. A bunch of 1sts and 2nds do 5d6, and several 3rds go as high as 10d6.