I have a slight problem with the caster having to cast the spell on the spot where his now non-existent target would have been in the second iteration, but that's not THAT bad a thing.
I suppose, though, the question is this: when the caster uses the spell, erasing the existence of the victim and so altering the past ten minutes of history, what does he remember himself doing during that time?
Obviously, it would be unfair of me as referee to tell you as player character what it was you did instead of what you actually did, and thus we have to play it through so that you can decide what you would do. However, I would wager that in the book, at least, the caster was never really specific about what it is that he remembers himself doing for that altered ten minutes. Thus there's no really solid argument to say he did not do what he did in the original ten minutes, except that he would not have done whatever it is that he did interacting with the person who he removed from the universe. I could have said that the caster is locked into repeating his actions exactly, and hope that it doesn't mean anyone gets hit by "friendly fire" because they're standing where the opponent was (or in the path) now that he's not there. What matters, though, for the sake of preserving time, is that there is a cause at the end point for what happens at the start point, and that means that the caster has to cast either the same spell or one confirming it. However, based on simple rules of cause, if the caster has not done anything significantly different in that ten minutes, then all the "chance" factors will come to the same total, and it isn't just that he has the same chance of success, but as if he had the same roll. Thus I wouldn't roll again for doing the same spell at the same time under the same conditions, and unless something really drastic changes in that ten minutes, I would conclude that the conditions are the same.
What sort of concerns me is the alternative, which is that having cast the spell against one opponent I can then pick another. That is, at 12:10 I cast the balefire spell against Captain Picard, and we change the history of the past ten minutes as Captain Picard vanishes at noon and Commander Riker takes over; then at 12:10 I target Commander Riker, and now at noon both Captain Picard and Commander Riker vanish, and Commander Data takes over. Give me ten minutes, and at 12:10 I hit Commander Data, and now at noon the three top ranking officers vanish. Maybe Lieutenant Worf takes over, but I can hit him at 12:10, and if we keep it up, I can take out the entire army, one person at a time, within ten minutes. Nor do I get wounded or tired nor even older, because every time I cast it, it effectively takes me back ten minutes.
Thus requiring the caster to repeat his action at the right time (and providing him with the knowledge to do so) preserves time against the possibility of an infinity loop and prevents the caster from duplicating his own action multiple times.
So this gives the would-be caster a total of... something like -165% penalty to overcome when trying to cast it?
Well, I haven't calculated it. Remember, though, that the penalty for bias only applies when you are learning a spell (or trying to create a magic device that performs the spell). It's going to be the usual balancing of what the caster says, does, and uses against the power of the skill (effectively obliterative, retroactively)--cost versus outcome. I would think that the biggest issue would be the balance of casting time--whether I think that the time you are investing in getting the result is appropriate for the result you are getting.
Come to think of it, this has to count as an Anarch spell - I can't imagine forcibly burning someone out of the fabric of time being anything BUT a slap in the face to the Creator's intended plan. So that may or may not matter...
Although I agree that it's unlikely that this would be an alliance spell, or even a neutral spell, I can see it as an
arcane spell--not holy magic at all. I can also see at least the possibility that it might be used by alliance characters against what we might for lack of a better term call anarch "fiends"--vampires, corporeal temporal demons, other undead, creatures deemed irredeemable by nature. I would probably assess a penalty against it as anarch holy magic for that very reason, even when so used (because it theoretically could be used against an enemy that was not irredeemable), but I would never say that God would not do something without contextualizing it. God would certainly object to using such a spell against sentient mortal beings capable of repentance, but whether He would also object to using the same spell against beings incapable of repentance is a much more difficult question.
And as to arcane spells, no one controls what you can do that way. If you also use holy magic, the questionable use of such spells might create negative sit-mods against your holy magic, but that does not prevent you from using the arcane stuff.
--M. J. Young