Seeking advice/input on appropriate damage for a modification of Vilano's Sling to a large group effect in an area of effect - changing it from affecting 1 stone on one target, to AoE with 100 stones.
Written at present as:
The goal is an area of effect Rego Terram spell which is centered on the caster, and ignores parma.
Is a +1 mag complexity modifier needed?
Is the range of damage to low or too high? It could be more random in the application of the damage, say: (stress*2)+5 damage?
I wish to avoid a lot of sub-roll, like potential 1d5 hits, then resolve each with a finesse check and +5 damage each if successful.
I know the muchkin factor has potential - I'm trying to avoid a little of that issue by asking, but not seeking to rehash that discussion. I've read it and other post like it which is why I'm seeking opinions.
I would point out that Group without size modifiers can affect more than 10 rocks, if their total "size" is less than 10 times the basic size for T:Individual.
I would also point out that, under vanilla Hermetic magic, you can't make a spell that slings a rock "in the style of Vilano" (thus bypassing Magic Resistance), then picks the rock again etc. You can make a spell that animates a rock, so that the rock keeps flying around, but the rock will be opposed by Magic Resistance even when at rest. Or you can make a spell that flings a rock "in the style of Vilano", but once out of the spell's grasp, it's over until you recast the spell.
That said, assuming "continuous" magic the effective damage is relatively easy to assign. I'd start from the damage you want to inflict, and look at the closest spell (say, wielding the invisible sling) that inflicts it, once (D:Inst) on a single target. Then, add a magnitude to make the spell's D:Conc, and assume that damage is caused every round. Then, boost the spell's T: to Group for a spell that affects an area large enough to affect 10 people -- adding modifiers to size if you wish. For example a spell inflicting +5 Damage to an area large enough to hold 10 people would be level 25 (Wielding the Invisible Sling +1 Conc +2 Group).
You can alternatively do it "Vilano style", but you'll have to keep D:Mom. In this case, I'd require a Qik+Athletics roll from every victim to avoid or reduce damage (12+ to avoid, 3+ to be hit only once rather than twice, botches stun/knockdown etc. you so you lose your next action regaining your feet), instead of a Finesse roll from the caster to aim the spell.
Alright, the first issue, is that you have an effect starting and stopping within your spell description. IMO, the effect needs to be kept going constantly, and therefore the objects so moved are subject to magic resistance. The concentration part, IMO is always acting on the rock, even if it isn't actually moving the rock.
In addition, you do need to perceive a pebble, and there need to be rocks in proximity to it that qualify to being in a group with that pebble. This is a very subjective determination that your SG will have to make every time the spell is cast. As an SG, I hate that (I'm dealing with enough stuff, and I might be miserly one time and over generous another time, and someone at the table might not like my interpretation of how this spell works today or how it worked last week). As a player, I like not having control over what I'm doing in a situation even less.
You seem to have a second "free" effect built into the spell where you can designate a spot that doesn't get hit by any of the stones so animated. How is this accomplished, if the stones are aimed with a Vilano style effect (ignoring the issue I first raised)?
Similar to ezzelino, I have some problem with the damage. Damage in Ars, IMO, should scale with the base effect, not with the magnitude of the spell. The Base effect in this example is hurl a stone projectile with enough force to do +5 damage. Being hit with say 4 stones, doesn't mean he get's hit with +20 damage, it means he gets hit with +5 damage 4 times and each is soaked individually, and damage is applied individually. This means a well armored opponent with a high soak will probably be able to shrug off such a storm. I'm working on the averages here, not the extremes where the soak botches or the damage explodes. I've botched enough damage rolls on the Incantation of Lightning, so I know it happens, it's just an outlier.
The best way to achieve a repeated Vilano-style effect is, I find, to learn something like invisible sling (or invisible shotgun, if you prefer) and then to master it for multi-casting. The end result is similar to concentration duration, only you're simply re-casting every round.
With a decent amount of mastery, you'll find the damage quickly stacks up anyway. Just be aware that blocking such an attack as a magus is really easy - warding against small stones is not hard, and wards of that type are binary.
I haven't given up the goal - which was to have a Vilano "hailstorm" around a Magus - it might take 2-3 spells to get it right and probably created as a magical device instead of spells. The flaw in the design with regard to the constant effect was glaring as soon as they guys pointed it out.
With regard to the damage I haven't got a solid idea yet on how to represent how many times a person might be targeted. i know each is doing +5 damage, but the volume might make that more risky even if each is only +5. Perhaps that is just where the dice roll comes in.