A player wanted to create a spell taht lifts an amount of dirt up underneath a target, then flips the earth around/ or drops it. Either burying or catching the ones on the moving dirt.
(base 3, +3 vision + 1 part, + 1 fancy effect, + 1 size, + 1 concentration)
giving this a level af 30 affecting about 100 cubic paces of dirt which really could do some damage.
If a magus is on this "disc" how does his parma affect this? my immedieate thought would be this is as a arrow moved by magic and would be blocked.
With how much speed does the dirt move?
this would be an aimed spell
how much damage could a spell like this do?
All terram spells seem quite easy to convert into damaging spells. Lifting a big amount of dirt on top of a anohter would be like a level 15 ReTe and parma could not stop this since it would be non magical when released.
I think your calculation might be off a bit-- if this is a part, it's still no more than an individual. The +1 magnitude for size gets you 10 paces, so maybe 2 paces by 2 paces by 2.5 paces. I'd shift the effect to opening up, erupting up and then pushing back down. You should probably cut it to voice effect and give it the bump to also effect stone, or you'll just get dirt and loam. I'm not saying that's ineffective, but cutting down to voice opens up a lot more terrain for targets. As you've got it written, I'd require a targeting roll or allow a quickness roll to permit the person in the area of effect the chance to leap out of the way.
He'd be unmoved by the earth. I'd have the earth just splash around him like a fountain.
Whatever speed you decide it should move it at. Is the spell designed to move it quickly and damaging? Just pour it on? It's Ars Magica, so designing a spell has a certain artistry to it. There is that...
I think so, or it should allow a quickness roll to escape.
I'd put it at +5, like getting hit with a lance. If you kick it up to stone and earth, then I'd bump it to +10.
Perhaps, but I'd definitely allow a quickness roll to escape the effect-- at that point it's uncontrolled and a shower of dirt. Some people are going to move a lot better than others, and manage to escape that effect. If you flung it, as discussed in the Flambeau section of HoH:S, then the targeting makes more sense.