Spell Penetrating

I cannot figure out with my own meager faculties how one spell or power penetrates another spell when used against it.

My example is with the massive granite wall spell that is in the other post. So a Cr/Te spell with a Sun duration creates a massive 7 pace high by 1.5 pace thick granite wall. Now I was wondering, if someone were to attack this wall with a spell or might power, are they simply attacking a wall of granite, a magical wall of granite, or a spell?

Meaning, if it is merely a wall of granite, then any simple Pe/Te or some earth elemental, ect ect attack would work as per rules against stone. But this spell using no vis at all, does not make true stone, so I figure this example is the wrong one.

Next would encompass both a spell and the wall simply being magical and as such then either it will need to penetrate the in-coming spell or that spell would need to penetrate it. I cant reason out which one is correct, but I am almost sure one or the other is the case. I am thinking the attacking spell must penetrate the spell that made the wall, but at what level? Does the penetration have to exceed the level of the spell? Does it have to penetrate the casting total of the maga that worked the spell? Does adding penetration by the maga that cast the wall spell, make it more difficult for the attacker to penetrate the wall?

((I have my own feeling which is the attacker must succeed in casting a spell that penetrates above the casting total of the maga that made the wall. So the maga makes a Lvl 40 Cr/Te wall with a 79 casting total, and any attacker must then hit and penetrate above that 79. Although a good argument could be made to say that the attacker must only penetrate above the 39 points of power that exceeded the Level of the spell. ahhh Ars you really are a thought exercise!!!! :laughing: ))

I know I am missing something, I always do. My method of thinking never pairs well with the mechanics, though my creativity groks Ars paradigm quite well.

Think of it this way: spells don't have Magic Resistance. They have to penetrate Magic Resistance.

If you want a "counter-spell" then the rules for that are in the core book: "Fast Casting" p. 83. In fast casting, you compare the Level of the original spell to the Level of the counter-spell. Magic Resistance doesn't come into it.

Does that help?

So a Archmage cast a Re/Co Lvl 5 Spasm...Hand with say a casting total of 80 could have the spell unraveled by a Pe/Vi Lvl 6 spell cast by a apprentice with a casting total of 4? At least by the reading on the fastcast section it seems to say that.

Can you build into spell additional magnitudes I wonder....

Ah well it seems fairly obvious that low level spells cast powerfully seem to still only be low level spells when it comes to unravelling them.

Yes. I think your suggestion of allowing more Magnitudes to be built into a spell, just to make it harder to unravel, is a good one. I think I'd allow it in my Saga.

Consider, instead, mastering the spell for Obfuscation, such a low level spell that is obfuscated becomes difficult.
The standard check to determine the effect of a spell when it is difficult is Perception + Awareness vs 15-effect magnitude, so that ReCo 1st magnitude effect needs at least a 15 on an awareness check (assumes mastery score of 1 with obfuscation).

I've always seen it that you can't affect a spell cast by another person like that, IMO. If you want to PeVi the incoming spell, you need to affect the spell AS it is being cast, which means you need to penetrate the archmages penetration. Good luck with that. On the other hand, if you want to stop an incoming Pilum of Fire spell, throwing up a stone wall in the way, surrounding yourself in a bubble of water or teleporting five paces behind cover all work fine and thats how I've always seen the fast casting defences working. P83 for instance says that
"The spell still takes effect, and the side effects of deflecting the spell may have to be dealt with."

Contrast with the muto vim guidelines on page 159
"If you want to cast one of these spells on a spell being cast by another magus, you must either be co-operating, or you must fast cast the MuVi spell. There is no other way to get the timing right. In addition, your penetration for the MuVi spell must beat the other magus' penetration total for the spell to be changed, unless you are co-operating."

Now all that said, you can get a lot of mileage out of a mastered (with fast cast) Unravelling the fabric of Ignem spell. A level of 15 will dispel a level 25+d10 ignem spell. Thats all but the most powerful ignem spells and anything higher level than that will struggle with penetration anyway.

Actually trleporting 5 paces away does not protect you from POF in 5th edition since the fire engulfs you as default, the "missile" part of POF being only for aesthetic value. Not how we play it, but this is what RAW says. Equally, I would agree that you need to beat the penetration of the spell. However, that is not RAW, either AFAIK.


The T:Ind is the item of fire created at the indicated spot (small 't' target). So, the fire is created a certain location, but by the time the spell is completed, that location is no longer occupied by the magus. Or something.

So ypu say that if I move 3 paces while you move your arms and shout stuff to invoke your magic you will never be able to hit me with an Ind target?

No, I'm not saying that, at all. I'm just responding to your comment that you don't play PoF and Leaping away that way. You didn't exactly explain how you play it, yourself, you know. So, one could say that you are saying that.

What I'm saying is that someone can leap away from these spells, much like you do. The RAW is sufficiently undefined to allow the wiggle room. If you want to pin me down, we could say that the magus can predict where the small 't' target is and deliver his Pilum to the intended small 't' target at the appointed time. The Leap is too unpredictable to adequately target... Or something.

As long as you can still be perceived by the casting magus, you get roasted (unless your MR prevents it). We do not call it POF anymore though, we call it "Touch of the Bonfire" since the RAW spell is not a fireball anymore in 5th edition.

What I was trying to point out if that if you go strictly by "a fire in THAT exact location" you can prevent getting roasted moving 2 paces while the magus is invoking the effect, and I found that quite funny actually. :slight_smile:


I still don't understand how you can defend against the spell with a Leap, if by RAW, fire is created at the small 't' target. Change the name all you'd like, the effect still operates the same way.
In my understanding or rationalization, the flying to the target is a bit more than a cosmetic effect...

It comes down to: if you cast a D:Diameter spell, will it follow the target?

It also relates to Wizard's Sidestep. In both cases you target the point where you think the target is. If it leaps away early, you can adjust. But if it happens at the last second the spell hits some empty space.

We've had discussions on those 2 points, and I think it was fairly divided. Pick one behavior and stick to it.