thoughts about Hermes Portal ritual spell

Hello,

I am trying to come up with some long term goals for my new character - he has Flawless Magic and Rego Terram is his strongest set of Arts.
Then I considered having him cast "Hermes Portal" ReTe 75. I know he is nowhere near capable of doing it now, but it could be a long term goal.

So, could a single magus cast both halves of the "Hermes Portal" ritual?
With Flawless Magic my character could (in the distant future) learn it with the Multiple Casting mastery ability. I presume my character would also have by then a Talisman and/or Familiar, both of which I believe my character would have a permanent arcane connection to.
So if my character is at one end of the intended "Hermes Portal", and the Familiar and/or Talisman is at the other side, could the magus cast "Open the Intangible Tunnel" ReVi 75 to the Talisman/Familiar, then while the intangible tunnel is open multiple cast the "Hermes Portal" ritual, at both ends of the intangible tunnel?

Then again, it is unlikely that a single magus could cast both ReTe 75 and ReVi 75. Not unless they had a Magical Focus in Teleportation.
At any rate, I am thinking about how to open a "Hermes Portal" behind enemy lines, without having to smuggle a magus behind enemy lines. Getting a raven familiar to carry a wand Talisman to the required location seems a lot more discrete.

On the topic of behind enemy lines, as a ReTe Magus you could guide a drone to the point you want. If that drone is your talisman than that's riskier but plausible.

However I'm not sure you'd want to open a HP given it's cost and permanence. A teleport spell would be just as useful (ignoring warping) for deploying troops. Given them an item which returns them via a circle?

I may be a little shaky on the theory of teleportation in an Ars setting. Where does the warping come from?
Are you thinking of a Group or Circle Target non-Personal Range version of "Leap of Homecoming" ReCo 35? Wouldn't that require requisites for equipment?
And you would need an arcane connection to the destination for the teleport spell. How would you get that?

I think a spell for teleporting a group of soldiers to R:Arc will be high enough to incur warping (single powerful effect, Ars p.167 dot point 2 and p.168), as it'll be level 30 or higher, and also unlikely to be designed for the group of grogs.
And yep, requisites for gear are needed when casting. That makes the spell harder to create but a HP is far higher level - so it might be a trade off (?).
And yep, an AC is needed to the destination location which is pretty easy to guide in remotely using another Rego effect. That requirement isn't removed by using a Hermes portal either.

I was inquiring whether casting "Open the Intangible Tunnel" to a Talisman touching the ground at the destination side fulfil the AC requirement for "Hermes Portal".

Keep in mind that Hermes' Portal is defined as "Mercurian Ritual" and there is no base effect guildeine and such. So it is clearly not fully integrated in the Hermetic Theory. There is no way to design other version with shorted duration or different range.
So it means that it is not entirely bound by hermetic theory, thus gives you some freedom to adjucate what is possible or not.

Before all, if a mage is willing to learn this ritual, collect the 30 paws of vis required, then master it and go the extra-mile to design a way to have Intangible tunnel working for dual casting AND that it leads to interesting story, go ahead, have fun.

I'd allow a single caster to do it... Cast the ritual, step through the portal on one end, cast the second ritual on the other end. Makes for interesting botch resolution, in any rate.
I know that portals are only supposed to be functional based on the simultaneous casting at each end point, but I find that to be a somewhat problematic proposition when you put that in the hands of a few magi, such as Flambeau Mercurians, members of the Cult of Mercury, or Merceris Magi. The logistics of getting two magi into position, coordinating timing are unlikely. While it is true that magi could conceivable communicate at long distance, it is less than likely for magi who have a stronger TeFo combination in ReTe than CrIm.

I don't think the timing would have to be that precise, as this is a ritual, but the ritual certainly has to be in the process of being cast at the same time on both ends at some point.

Not necessarily. Using Transforming Mythic Europe, you can cast Rego Terram teleportation spells as a base (literally, a slab of rock as a platform), and as long as the weight of additional stuff doesn't exceed 1/2 of the weight of the platform, you don't need extra requisites. (TME, pg. 107, callout, "Instant Transportation and requisites). It does, however, explicitly state that AM5th doesn't specifically mention requisites. As such, if you troupe wanted to, they could require it. However, some of the spells in the core rulebook don't require them - such as the flight spell, or the Frog's Leg one.

Using a ReCo, then, you could teleport without requisites as long as the carried equipment doesn't exceed 1/2 the weight of the person...heavy encumbrance, I think? (looks into TME) - ah. Encumbrance 3 or greater.

This is the insert on page 107, and the false comparison of comparing Flight and Gift of Frogs Legs to teleportation with requisites suggests that you can't use PeCo to kill someone if they are wearing armor, either. It ignores the idea that the spells still affect the body, and clothing is carried along incidentally, and the spell doesn't actually affect the spell. I reject the premise that Gift of the Frog's Legs uses the base guideline for teleportation. There are a number of spells in the core book that don't have a corresponding base guideline actually printed. Then it's a legacy spell.

The insert on page 107 is much more nuanced than what you say it says. It says if you want requisites for teleportation, you make these spells harder to cast. If you don't want requisites, they're easier to cast, and as a bit of a governor on the ease of these spells being cast, use the formula you outlined above to determine the governing form for teleportation.

It just occurred to me that a level 75 "Open the Intangible Tunnel" ReVi Gen would have to be a ritual also.

Essentially no I don't think you can as you can't use your familiar to target the HP spell, as you need to target the destination location and not your familiar. You'd need your familiar to get another AC to the actual location back to you, so you can then target the OtIT and HP. HP needs a fixed location.
It's still solvable by teleporting the familiar back to you with the AC in their possession though, it just takes two steps.

No worries, I understand that about the Familiar.
Admittedly I was thinking about the Talisman mainly. If I understand "Open the Intangible Tunnel" correctly, if you use the arcane connection to the Talisman, then the magus is effectively touching the Talisman, and thus the mage's touch is extended to whatever the Talisman is touching, which can be the ground and hence what should be needed for the "Hermes Portal" spell.