Opening the Intangible Tunnel

Can it please be explained what is the point of this spell?

It's range is arc and as you can cast spells on folk at distance with an arc connection with pretty much any spell, how does it's casting benefit a magus?

Does it essentially give spells with R : per/eye/voice that added distance?

Thanks once again

There is a difference between an Arcane Connection and R:Arcane Connection. Just because you have an Arcane Connection doesn't mean you can cast spells at that range, without a spell designed to take advantage of it. If you are using an Arcane Connection to boost a Pilum of Fire, the recipient of the spell still needs to be within Voice range of the spell. With Intangible Tunnel, however, you can open the Tunnel and send the Pilum of Fire through the Tunnel, whether he is just outside of Voice range or halfway across Mythic Europe. Without Intangible Tunnel there is no way for the Pilum of Fire to affect the intended recipient if he is out of range.

Edit: keep in mind that in all cases of having an Arcane Connection that you get to boost your penetration by possessing said connection.

As Jonathan.Link says, only spells with range Arcane can normally be cast at range Arcane.

Yes (although not for Personal). It does the same for Touch and Sight range spells, of course.

You could have invented Arcane range variants instead, but casting via an Intangible Tunnel allows you to access that extra distance without increasing the magnitude of the spell. This is important because you might not have sufficient Art scores to be capable of inventing (or casting) the spell at Arcane range. Learning a single Intangible Tunnel allows you to "convert" all your other spells to Arcane range (assuming the tunnel is of sufficient level). The other big advantage is, because the magnitude is lower, if the target has Magic Resistance then your net penetration will be greater if you are casting down an Intangible Tunnel (of course, you need to penetrate with the tunnel too).

The main disadvantage is that you need two spells (and possibly a third --- Maintain the Demanding Spell) to do the job of one. But once the tunnel is open you can use it to cast many spells. If your target has Magic Resistance, then the other disadvantage is that you need a good penetration with both ReVi (for the "delivery" system of the Intangible Tunnel) and whatever your "warhead" is (CrIg, for example). There is also a small risk of the target being aware of the tunnel and casting spells back down it at you.

An extended example may be useful.

EDITED: There is debate over how Aegis affects incoming spells. I am using the clarification found in Hermetic Projects, which I cite below: if either the target of the spell or the caster is inside a hostile Aegis, there is a casting penalty of 1/2 the level of the Aegis.

Cain and Abel are magi who have declared Wizards War on each other. They have fixed arcane connections, have each other's signature from hate mail written over the years, and know each other's Hermetic names, but no other sympathetic connections. Both have Parma of 4, Penetration of 3, and are protected by an Aegis of 25.

Cain invents the following spell:

Spontaneous Combustion, CrIg 30
R: Arc, D: Mom, T: Ind
The target takes +15 fire damage.
Base 10, +4 Arc

Presuming Abel has Ignem 10, Cain needs a 52 to affect Abel with this spell: 52 -12 for Abel's Aegis = 40 - 30 spell level = 10 penetration + (3 x 7 = 21) = 31 penetration total, just enough to overcome Abel's Ignem resistance of 20 Parma + 10 Ignem. You can decide for yourself if a 52 is moderate or hard, but it's certainly not easy. For magi of this level, inventing a level 30 spell probably took a couple of seasons.

Abel, on the other side of the Tribunal, is instead using Intangible Tunnel. He invents a level 15 version of the spell, substituting Diameter duration for Concentration. He also develops the following spell:

Pull My Finger, MuAu(Co)
R: Touch, D: Diameter, T: Part
This effect transforms the air entering the target's lungs into a noxious sulfur vapor that causes +3 damage each round for 20 rounds.
(Base 3, +1 Touch, +1 Diameter, +1 Part, +1 Corpus requisite)

Presuming that Cain has arts of 10, Abel needs a 37 to succeed with first the Intangible Tunnel and then Pull My Finger: 37 a 12 for Cain's Aegis = 25 - 15 for spell level = 10 penetration + 21 = 31 penetration total. A 37 is still not easy, but is certainly far easier than a 52. Abel had to invent two spells instead of one, but they were both easy to invent. The strategy is not without risk; if Cain has a way to percieve an Intangible Tunnel (but only if), he can attack back through it. Abel could develop additional spells, such as a a PeCo 15 to inflict Medium Wounds on Cain, or a PeVi spell to close his own Tunnel, and so on and on, in the way of Hermetic magi through the centuries.

Good idea.

The casting penalty only applies if the caster is standing inside the hostile Aegis. Presumably each are standing within their own Aegis, and lobbing spells at the other.

The penalty isn't -12 for casting a spell from outside of the Aegis, it's -25, the level of the Aegis. There is a penalty, worse than if you were standing within the Aegis.

Which brings up an interesting conundrum. Is a spell cast through an Intangible Tunnel effectively within the Aegis for determining the penalty to the casting total?

The tunnel only changes the range at what you can throw spells, not your location at the time of casting.

Spells passing into an Aegis just have to penetrate the level of the Aegis, there is no casting penalty (see ArM5, page 161). In this case, because the characters each have a Magic Resistence of 30 (i.e. greater than the Aegis level of 25) the Aegis offers them no effective protection.

The caster is where-ever he is, the terminus is where-ever it is.

So, if the target of an Intangible Tunnel is within an Aegis (that the caster is not also within, and that Aegis is hostile to the caster), then the caster does not have his casting total penalised (because he is outside the Aegis). But the Intangible Tunnel spell (and spells subsequently cast down it), need to penetrate the Aegis level, because they cross over a hostile Aegis border.

So, if the spell is cast outside of the Aegis, you get the best of your Magic Resistance or level of the spell, while if an enemy magus storms your covenant, puts boots on the ground within your Aegis, you get the benefit of the Aegis (reduction in casting total) AND the benefit of your parma. That's bass ackward, IMO. In almost all circumstances, it is to my advantage, if I'm an enemy magus, to cast my magics from outside of the Aegis.

I can see a strict reading of the text of Aegis of the Hearth allowing you to understand what you're saying, but the implications that an Aegis protects you better when the enemy is inside the castle is a bit of a stretch.

The Aegis applies NO penalty to spells cast from the outside. It either blocks the spells completely or has no effect. Just like every other form of magic resistance.

Now you might allow magic resistance to stack when it doesn't say otherwise: Parma, True Faith, Relics, Might Score, that Demon possessing you but the Aegis isn't special in that regard.

Just add the level of the aegis to your parma total and you will be quite secure. Not RAW, but it works well.

Edited my original post as we debate the interactions of Intangible Tunnel and Aegis.

Only if the target magus has a greater Magic Resistance than the Aegis level.

In established covenants (i.e. where there are senior and / or specialised magi who cast a high level Aegis) it should be quite common for individual magi to have lower Magic Resistance than the covenant's Aegis.

I have found a clarifying passage from Hermetic Projects:

Emphasis added.

So, in our example, because Cain and Abel are both targeting inside a hostile Aegis, BOTH MAGI have a -12 to their casting totals, one half the level of the Aegis.

No, that just means if you are standing within a hostile Aegis you get the casting penalty. In your example, neither Cain nor Abel are standing within an Aegis hostile to them.

The target is inside a hostile Aegis and therefore there is a casting penalty. The only caster is outside the Aegis. I don't see how the sentence can be stating that the target has a casting penalty. It must be affecting the caster, when his target is inside a hostile Aegis.

I'm not sure what you're really trying to say here.

If I'm outside of the Aegis, I have to beat the better of the Opponent's MR or the level of the Aegis in my Penetration total.

If I'm inside the Aegis, I have to beat my Opponent's MR + Half the Level of the Aegis in my penetration total. If Opponent's MR and Penetration are held constant, in all cases it's more advantageous to stay outside of the Aegis and fling spells.
If we have an attacker with a Penetration total of 41 and An Aegis of 40, and the defender has an MR of 39, he wins by staying outside of the Aegis. The minute he steps within the Aegis, his penetration total drops to 21 (half the level of the Aegis 40) and he therefore cannot affect the defender. That's what I mean by bass ackward.

The section you are quoting from is talking about both the "target of the Intangible Tunnel" and the "caster of the Intangible Tunnel" casting spells through the tunnel.

I can see why you are reading it the way you are. But I know it is not the author's intended meaning :wink: the author could have, perhaps, worded that sentence better.

This is just an artifact of the numbers you are picking. You are just considering an attacker who can blast through the Aegis and an opponent who has a MR close to the Aegis. Perhaps this is a common situation in your saga, but it is not clear why it must be.

If the attacker has a Penetration Total of 41, there is an Aegis of 40, and the defender has a MR of 15. In this case, the attacker will be able to Penetrate both outside (with an excess of 1) and inside (with an excess of 6) the Aegis, but will have a greater excess Penetration when he is inside. Which may mean he can sucessfully cast a greater magnitude spell when inside. So, it is possibly advantageous to move inside.

If the attacker has a Penetration Total of 41, there is an Aegis of 50, and the defender has a MR of 15. In this case, the attacker cannot Penetrate from outside, but if he moves inside his net Penetration becomes 41-50/2 = 16, which is sufficient to beat the defender's MR of 15. So it is advantageous to move inside.

If the attacker has a Penetration Total of 41, there is an Aegis of 60, and the defender has a MR of 15. In this case, the attacker cannot Penetrate from outside. If he moves inside his net Penetration becomes 41-60/2 = 11, which is still insufficient to beat the defender's MR of 15. However, it may still be advantageous to move inside, because the attacker can perhaps cast a lower ranged, lower magnitude effect. He only needs to increase his Penetration by 5 (i.e. drop the attacking spell by one magntitude) to be effective from inside, but he needs to increase the Penetration by 20 to be effective from outside.

I admit I'm not doing a sophisticated analysis. Also writing while on my phone. High level Aegides, above 30th become expensive in Vis costs. Also requires someone with many botch reducing capabilities, mastery, virtues, golden cord to mitigate the large botch risk of 9 or more both dice when starting at a 40th level Aegis. That's just in Vis. If the Aegis has to penetrate as per RAW then you need to use Wizard's Communion and add 1 botch per magus in the communion. 8 pawns of Vim Vis per year alone is going to be tough, especially if you have to farm your aura for the Vis.

I think the Aegis need some revision. It reads word for word from 4th Edition as I recall. That isn't a good thing.