Penetration Rules

OK.. as you know i'm preparing my Ars magica Campaing...

Some of the players already played Ars Magica, but only the 4th edition... Yesterday we were chating about the rules and the penetration rule in 5th edition provoqued a ravoc...

I know that the in game explanation for the change is that the greater the magic less magic energy is used to pass the target magic resistence...

Why penetration suffered such a dramatic change between the editions? Game balance? In game justificative?

Isn't strange that the magi pass a lot of time creating and studing a powerfull spell, but the greater and powerfull the spell is less chance it have to pass magical resistence?

Not strange at all. When my old group switched to the new edition, this change didn't even cause a ripple. It makes much more sense. You said it yourself; the spell is more powerful, thus the remaining energy to Penetrate is less powerful. Just because the magnitude is higher doesn't put more power behind it. In the old rules, my PoF was just as powerful as my BoAF, same casting total, same penetration. Being a higher lever just made it more damaging, not more Penetrative. And, in the old rules, once you learned BoAF, there was never any reason to use PoF ever again. Now it makes sense to have both.

Besides, I have noticed that Parma scores average lower than they used to, so it balances out. There is also many methods to improve Penetration, such as Mastery and Arcane Connection multipliers (in fact, it is this multiplier that made Penetration a relevant ability, whereas in 4th ed it was unimportant).

So, In my opinion, the new Penetration rules makes it into the top three best revisions of ArM5 (it comes in at #3; Mastery is #1 and streamlined Spell Magnitude guidelines are #2).

I recall David Chart saying somewhere that one of the goals of 5th edition was to make Magic Resistance more valuable so as to emphasize the significance of Bonisagus inventing the Parma Magica (as has always been described in the setting).

In any case, MR is much rarer than in previous editions. Secular and religious leaders still have some innate Magic Resistance, but MR is now largely restricted to those favored by God (Guardian Angel or True Faith), creatures with a Might score, and Hermetic Magi.

The inclusion of Sympathetic Magic in the Core rules means that it is now easier to improve penetration that way too!

Hope this helps.
~ Gremlin44

good points =)

I will discuss this out with the players!!!

The new MR rules also keep the low-level spells relevant. You now have an interest to cast PoF rather than BoAF - more penetration. [Edit: as Marko said...]

Personally (at risk of being flamed here), I prefer the old rules for magic resistance and penetration. The new ones just don't make sense to me. IMO, weak magic should not be better able to penetrate magic resistance than strong magic.

I'd tend to agree with LT, but I also firmly believe that "logic" and "common sense" have little place in a discussion of magic rules. They just muddy the magical waters.

One houserule that I've used in the past is, similar to Enchanting Items, allow any spell to be designed with extra levels dedicated toward penetration - those built-in levels count double, on top of any regular penetration from a good casting total. If you can do it with an item, you can do it with a spell.

(logic, common sense - ick, ptooey!) :laughing:

I don't understand why you consider it to be weaker magic. PoF or BoaF, my casting total is the same. If I am putting the same energy in either spell, how is one weaker than the other? Just because one is a lower level? Well, that just leaves more energy left over for something else, such as Penetration :smiley:

Hmmm... that's an interesting one... though at this point, I have so many house rules for my own, I'm thinking of just writing my own edition. :slight_smile:

But I think you're looking at it the wrong way. It's not the spell that penetrates, it's the magus. The spell complexity/effect saps power from the magus that he would otherwise use to force his spell through resistance.

A magus can only muster a certain amount of energy. The simpler or smaller the spell he's then using, the more potent he can make his casting.

And I think it opens up more options for play, too. If you know you can't penetrate the dragon's defences with your "one shot is all you get" dragon killing spell, then you need to find ways to boost your penetration, essentially find a way to use your power better.

It's a matter of how you view magic working. I understand that view and I have played games in settings where magic worked that way. However, I don't think it is the correct way for magic in Mythic Europe to work.

Of me, the core of Mythic Europe is the idea that it is a vision of our world in which myth and folk lore are real. Now, I know that Ars Magica magic has never been terribly close to "real" medieval magic (understatement). Still, I feel that this change (and many other 5th ed changes to the magic system) actually moves it further away from that, where I would have perfered to see this edition move the magic closer.

Now, I'm sure people will disagree with me (frankly, I'm stunned that anyone agreed with me), and that's fine. If it works for you and you have a fun game, that's what counts. It doesn't work for me and it detracts from my enjoyment of the game, so I'm going to change it.

I am one of those who don't agree. You can be very powerful, but so can your magic reistance, you need a system to breach that resistance or bypas it. not some "that was my best shot, it won't work, forget it, I'm going home" but a more gradual decrease in effectiveness. Now when your ball of abysmal flame at sight range does not work, you can go to increasingly low level spells and hope to burst through.

Mmm. I prefer to think of it as slipping past a wall - you can use a giant hammer or slip a knife through the cracks, as you get more powerful, you can punch bigger things through the cracks. To use a D&D analogy, at strength 1, you can't lift a hammer. At strength 5, you can, but the guy with Str 18 and a dagger is still more effective. Sort of.

Ech, it's a YMMV thing, but it does have massive implications if you start houseruling things.

I agree with you. I just disagree about how to achieve the effectiveness. To me, the idea that a 5th magnitude spell doesn't penetrate, where a 1st magintude spell does is like saying if I hit you with everything I have you ignore it, but if I lightly tap you I knock you over.

Ultimately, it's the idea that penetration is based on the "extra power" left over after spellcasting rather than the power of the spell itself that doesn't work for me. I would rather see a magic resistance whose effectiveness was based on the level of the incoming spell, letting magi ignore 1st magnitude spells and fear 5th magnitude ones. Admittedly that is not what 4th ed magic resistance did either. There magic resistance was based on the power of the caster and had nothing to do with the power of the spell, which I still find more intuitively acceptable that the "energy loss" system of 5th ed.


Yeah, but a Str 18 guy with a great sword is more effective that a Str 18 guy with a dagger... which is where the analogy doesn't hold because here it works exactly the opposite.

If the idea of “leftover energy” troubles you, there are other ways of thinking about it. Even a powerful wizard can be affected by well-crafted small magics. It’s just easier to make someone sneeze than it is to kill them, and that’s why it’s easier to get by magic resistance with a sneeze-spell than with a death spell.


Other than the fact that 5th edition rules say so, why should a powerful wizard be affected - indeed be more likely to be affected - by small magics.

Because being powerful don't mean being invincible.
And on the other hand, if you have an X amount of energy, assuming that magic is using the same system than the life, it's more difficult to develop the energy to kill than for say hello.
So, on your X amount of energy, if Y is used for say hello, then >Y is used for kill. Then, you have X-Y energy left to try act on your "victim", which is bigger if Y is small.

Your casting total is your money/ a low casting total is small amount, high casting total is a fortune. Some is used to buy the vehicle and some used to pay for fuel. Magic resistance is the distance to the target.

You buy a small motorscooter (small spell) and have money for a cross country trip or you buy a motorcycle )big spell) and have enough for a single tank of gas. No magic resistance is looked at as a 1' trip. You can walk your bike there using none of the gas you bought. So it always makes it as you don't have to turn on the engine (so zero or neg resistance doesn't matter, the engine is never turned on). Low magic resistance is a ten mile trip, your one gallon of gas will make it as will the full country worth of gas. High magic resistance is 400 mile trek. The fancy motorcycle does a lot more and is a lot fancier but it just doesn't get you there on the one gallon of gas you could afford. The smaller cheaper vehicle crosses the distance because you can afford huge amounts of fuel.

To make this analogy go further: PEnetration skill/multipliers is your gas efficency. A high pentration is a high gas mileage or fuel additive to make things go further. Arcane connection for example is a short cut that cuts down the distance

Wonderful story!
Like it!

My favored analogy is that MR is a kevlar vest, spell magnitude is bullet size, and casting total + penetration is energy. If someone hasn't got any armor on, a shotgun slug, even moving slowing, might blast 'em in half. But once they put on some armor, they're spreading the force of that slow slug over their entire chest, and bullets that put the same amount of energy on a smaller area are more likely to punch through.