Spell critique: Ballista of the Magus

Posted this on Erik Tyrrell's list of 10-15th lvl spells, and got no reaction to it. I don't know if it's good or bad, but I think this spell is more or less correct. Serf's Parma however as I post this away from home and my books.

Ballista of the Magus CrTe 15
Requisite: Rego
R:Voice, D: Mom, T: Ind

This spell creates a sliver (a "spear") of stone and propels it towards a target, doing +10 damage (or +15?). On Timofey Ex Miscellaneas version of the spell the "spear" vibrates in flight, but does no extra damage.

Base 3, Voice +2, Requisite +1

This spell is a bit ad-hoc in that there's nothing in the guidlines to make Terram do damage. There are however spells that justify this use of Terram. The most obvious is "The Crystal Dart" in which you transform an ordinary rock into a dart of crystal and propel it towards the enemy in such a speed that it does +10 damage. If you have time to transform and propel during a Momentary duration, you should have time to create and propel during the same duration. Whether the damage for the spell should be +10 or +15 is also a bit ad hoc but the stone "spear" is bigger than the dart so it should do more damage.
Ok I await your objections, and if you just want to post on how cool this spell is you're also welcome to. :wink:

I don't have any problems with the spell as written. It seems very practical and I'm sure a terram magus who's creo was stronger than his muto would develop it in preferance to the crystal dart.

I have a slight preference for + 10 damage rather than +15 for balance reasons rather than because it is more logical. +10 damage puts this flyng shard spell at the same damage as crystal dart and piercing shaft of wood (when using a staff). I'd justify it having the same damage as crystal dart because it has the same "force" behind it (please oh please don't take this as an opportunity to re-start the rego motive force /iorn man discussion).

If memory serves (and it might not) PoF is level 20 and does +20 damage meaning, that with the way ignem scales, a level 15 version of PoF does +15 damage making it a better spell for the same level when it doesn't even have a requisite. My opinion is that ignem should be a better offensive choice becase I like ignem flambeau to be effective and there are so many other things that one can do with terram. But this is all personal preference.

But Crystal Dart is 10th level and do +10 damage. Also Ballista (and tCD) has a requisite, which Pilum hasn't. So for it to have +15 damage wouldn't be broken by any means. Also this spell is one magnitude higher than tCD which is 10/10.
HOT

  1. Ignem is the pre-eminent raw-damage Form - the other Forms are all better at other things, but Ignem does the most damage for a given GL.

  2. Ignem is the only Form where damage scales as a direct linear function of the the Guideline Level. There is no reason to suppose that you can make a Terram spell do +5 extra damage by adding +1 Mag - only Ignem provides that guarantee.
    (Even Perdo Corpus/Animal cause Wounds not Damage, and it's not an unbounded linear scale).

  3. Create Terram is not normally in and of itself damaging - it is ... rock and earth.
    Rego Terram moves things and indirectly damages other things if you hurl something heavy, moving fast.

You can argue that you are creating a great boulder and hurling it, but you should measure the damage by looking at a hurled boulder...
(But also checking that you don't leapfrog Ignem).

As a summary - it might be better to go for, say, +13 damage rather than +15.

My guideline for damage through Rego at the base "unnatural" movement is to consider a strong (+3 Strength), skilled (3 Ability) warrior attacking a subject with a defense of 0, adding in what ever weapon damage bonus is appropriate. I know that this works out for Crystal Dart, and comes close enough to other spells, that it's my standard guideline. For additional magnitudes I'd probably allow a +1 which should discourage pumping up huge levels.

Now, this will mean that different forms will do different amounts of damage at the same level spell. I am very fine with this.