Second Sight is very common for magi. Why avoid it?
Do note, though, that Second Sight must also penetrate. I will double check, but I am pretty sure that is the way it works.
Nope.
The intention is to have names of airy spirits the theurgist (Propolos) can draw on, summoning them and convincing them to use their powers. Hence, definitely an Entourage.
I have a question regarding this - I assume it's enough to summon the spirit with Momentary duration, based on the assumption that it can return to the things it is the spirit "of" at its will once the summoning spell no longer binds him (Propolos has no intention of holding these spirits by force). Is that acceptable, or would such a feat require a longer (Concentration?) duration? Or more magnitudes? Or a separate spell to dispatch them on their way? Or won't be possible at all?
Less diplomatic theurgists can bind the spirits into items once summoned, and command them by holding the items. Propolos is far too respectful to his spirits to do this.
I take Joo's "nope", and raise it by +1. Edit: A favored House Rule of mine is that InVi Might-detection spells don't need to penetrate too, unless the beastie has a particularly deceptive nature (a Faerie whose "shtick" is to disguise as a mortal, say). It just makes more sense that you can sense the Might 50 godling more easily than you can the Might 1 lesser airy spirit. If you agree to this house rule, I could go all Hermetic, as I wanted to initially. However, that's a House Rule. Under RAW, InVi spells need to penetrate....
The idea is to work differently. But again, if that's a problem, I'll go conventional.
I am calculating a Lab Total of 68, so I think 35 is well within reach.
I need to research Second Sight and Theurgy before I can give more answers.
My calculation was
So he can invent it i over two Seasons [Edited out mistake]. The thing is Propolos also need to Penetrate, and to do so several times (in order to succesfully summon the spirit, he needs to amass Spell Level - Might equal to Might, so with a level 35 summoning spell he needs to penetrate six times). Popolos just barely manages to penetrate as-is. I suppose he could use even more Art vis to increase he Penetration, or something. At any rate, I'll lower the Arts and think it over.
Another option is to increase his Penetration and take advantage of the True Name being an AC.
Note that the entrouge thing is strictly RoP:M, it has nothing to do with Hermetic Theurgy. Edit: It is just using the ReVi summoning rules, along with the rules on the names of airy spirits, given in RoP:M.
Yeah, that certainly affects the penetration [and I forgot to include it in my totals] - but that doesn't work against that spirit you run against mid-adventure that you can't see because you don't have Second Sight.
Oh of course not, but I meant that would help binding your Spirit Familiar to use the shared senses bit.
In addition to the Familiars discussion, I've been thinking of creating a Companion who's a Magical Character (all those RPGish capital letters!).
So...it looks like we're settling on a base Might of 25 for the "standard", fairly independent familiar, with 15 for an "extension" familiar, and something higher (whatever the sphinx ends up with, I guess) for a really powerful but really independent familiar.
What should the base Might for a Companion be? Mark suggested 15 (the book's guideline). I'm hesitant to make them less powerful than familiars, especially since they'll be less able to earn XP's (they won't benefit from the magus-familiar bond). I can though see some players giving them a lower Might just to make it easier for them to earn XP's.
How about a Magical Grog? 5, or something higher?
Thoughts?
Scott
Yeah, I got Penetration 3 for that, but forgot to add it up when calculating the penetration total.... I think Marko is right and I can do it with significantly less Arts. Now, the guidelines say that Te+Fo should equal Might for me to be "accepted", so even with a focus I strictly need Re 20 and Vi 20 - but I'm hoping my silver tongue (read: SG courtesy) would allow me to sail through on lesser Arts...
If you are interested there are 'lots' of spirits of relatively high might scores that are available in Ludovico's entourage for anyone to play.
YR7,
My suggestion is to focus on the Daimon type of theurgic magic and take full advantage of your Mercurian Magic as well as taking Hermetic Sacrifice, to be able to use them cheaply/regularly. That way you can bring such rule-bending quasi-non-hermetic stuff to the table that you have a unique feeling 'niche' in a group where there are already two other vim characters, one of whom is also spirit-magic focused. We can both broaden out into each others respective areas of spirit magic later. Be afraid Marko.
I wouldn't worry about having a Parma of 6 if you already going to have a spirit familiar of might 30. Not if you are worried about penetration on your daimon spells as is. You should be investing in True Names and your Daimon Spells, IMO. Parma is for people who aren't getting their MR from somewhere else and who want to go out and fight things toe to toe, rather than send spirits out to squish things. 
Marko has his own perfectly valid build/design ideas, but I think he frequently forgets the 'niggling details' that empower some other tracks of thought and design.
Does no one have any thoughts on the Might of magical companions and grogs?
Scott
Alrighty, new character at https://forum.atlas-games.com/t/character-sheets/2829/28
His stats at gauntlet are here, and his advancement to season 80 is here.
I've lowered the Arts and increased Abilities as requested. The only Abilities not "up-to-par" are Martial ones - he ain't going to do much dirty fightin'.
The great liberty I've taken is to assume he has access to lots of lab texts. He spent one season (10 XP) in service to the Cult, and in return was granted access to standard Hermetic spirit (not Heremtic Theurgy) lab texts for three seasons. He also used a lab text for Gift of the Bear's Fortitude and his Vilano-clone spell (Tearing the Flesh of the Mother), supposedly from his parens or magi he managed to befriend in his travels. This means he only actually developed from scratch his two Invoke the Pact spells and the three powers invested into his Talisman and Familiar.
Another major liberty is the assumption that his familiar, the Matron, agreed to bind as his theurgic spirit familiar despite the fact that he's a bit short on Te+Fo (which is 40 instead of 60 - but the 60 is only a "guideline", not a harsh rule).
I assumed his familiar (+5 Int, 0 Magic Theory) aided in instilling the powers in the familiar bond, but not with other lab totals.
To stay on the safe side, I assumed a separate spell is needed to return an airy spirit to his demense (once it is summoned elsewhere). I set the base level to 15, the same as summoning him from his locale using an arcane connection (its name).
I assumed only 1 Warping Point per year, as he bears no Longevity Ritual.
I did not apply the -1 Encumbrance penalty due to his staff - still waiting on a ruling whether a wizard's stuff is indeed encumbering.
As part of his makeover, Propolos now has 10 allies in his entourage. I assumed Agency rules on their number, even if they would be actually played when summoned (which I don't foresee happening that often). I provided brief statistics on all, but this is just off the top of my head - anyone feel welcome to change them, and I may do so myself.
I could always find what to do with more XP, and this Art-deprived version of Propolos has a bit less oomph, but I'm happy enough with the character as-is. So if there would be no further critical feedback - I'm ready to begin the game Marko.
Cool. I will kick things into a higher gear by this time tomorrow 
What do you want to do about his staff and Encumbrance? If it's Encumbrance for anyone else, it should apply to a magus as well, though maybe it depends on whether it's carried as a walking aid or as a weapon.
Scott
Personally I don't think a Staff should really add to encumbrance, but that's just my two cents.