As written, I believe you get all three of the abilities when you buy your first rank of Sorcery. Each purchase of Sorcery gives you more Marks to use; that's it.

Seems a bit powerful to get all of the abilities, but that's all you get with Porte (as opposed to the others tacking on more versatility and options).

I've been tempted to do a rewrite, but as no one at my table is using Porte to even see how well it works, I really don't think I need to do a rewrite yet (although I'd love to see some other abilities, like Catch, make a comback).

Just saw this post after commenting in agreement with LibrariaNPC in response to your other one on the Sorcery Advantage, Harliquinn, so forgive the double posting, but yes, from my understanding, Porte is entirely front-loaded, the Sorcery Advantage just allows you to maintain more Marks each time.

The other thing to remember is that Porte NEEDS flexibility.  If you only have one major mark and it happens to be a bit closed off, you are stuck in hell for the rest of your (short, torturous) life.  I don't know if I'd be willing to risk a walk with only one endpoint.  Porte is a bit boring from a dramatic perspective, but probably one of the most world-breaking as far as actual effects go (the logistics angle is what propelled Montaigne to the top).

Having played and run for Porté sorerors in 1st ed, I have a couple of things to add.

The sorcery was somewhat of a letdown at low levels originally.  "Cool, a sorcery that lets me teleport!".  But only once I've bought 4 knacks up to rank 4?  That's a bit poo.  Hold on, half-blooded can't do it ever?  So I spend 40 of 100 points and then spend over 80 xp and finally I get to teleport?  Blow this for a game of (teleporting) soldiers!  Whatever you do, Walk has to be available at with just the Sorcier background, and probably with just the one Advantage.

Porté got more stuff in the Montaigne book: Catch was a fun knack, handing-off is very useful, Walking away from a fall can be life-saving, Gateways actually give massive logistical advantages.  I can imagine there being extra abilities that are available if you sacrifice a Minor of Major mark.

In my campaign, I have a Vesten Warrior who is determined to acquire the Porté Sorcery advantage somehow. In fact, he even decided his first Story will be about it, just after he kidnapped a minor montaigne noble with Porté.

I´m inclined to allow it, creating some form of house rule (probably some nasty variation of Hexen), but I don´t know Porté too well, not sure how it works in combat, how many nobles have it, the full extension of the powers, the nature of the plane they use to travel by. I intend to acquire the Montaigne Book from 1st edition, but someone give me a few tips or sugestions in the meantime?

Given the fact that Porté is a blood-only transmited sorcery type I am sure it would involve either parts of the noble or his blood.

Also kidnapping? Seriously? A hero using such methods?

IF (big one) that's heroic, the path of acquiring the Porté Sorcery should be a big one and might be plagued with distrust and fear until he dfemonstrates he is using it well.

As per mechanics, 4-5 steps (don't recall exactly) should grant 1 major mark and 2 minor marks as per the book. If you want to reflect that it is an artificial thing, make it 3 steps but only giving a minor mark access.

Honestly, I think I would like to quote from the top of p207 here:

'Many aspects of Sorcery are intentionally powerful, to the point of being worldbreaking. If you are reading this Chapter, see a Sorcery power, and think to yourself “Yes! That is so strong! I can destroy anyone! Nobody can stop me!” then we’d like to be the first to congratulate you on your new career as a Villain, and advise you to start the entire process of Hero Creation over again.'

Porte is a sorcery that's usefulness is almost entirely dependent on how creative one gets with it. Where other Sorceries like Glamour, Hexenwurk and Dar Matuski are fairly defined in what they can do, Porte (and in a different way Sorte) tends to be a little more loosely defined.

In its most basic use Porte is useful for always having your sword available or being able to always get back to the ship, but there are very creative ways one can use it in other senses.

Off the top of my head, a Porte mage could remotely activate a device by marking the trigger and pulling it through while safely out of harm's way. Perfect for a Sorcier turned Rilasciare anarchist. Any sort of sabotage is nicely achieved through Porte. Mark a part holding together a carriage's axel or harness, then pull it through when they attempt to pursue you.

And that's just with minor marks. With major marks the possibilities open up tremendously. All you need to remember is that while Major marks are usually used for large objects, they don't always have to be.

For instance, an enterprising Sorcier spy/thief could carry a crossbow on him. He locates the building he needs to get into, and marks one of his crossbow bolts. He then simply fires the bolt through a window and into a wall inside, and then steps through into the building.

Or, the sorcerer trains a cat to go where he wants it to go, and then blood marks the kitty's collar, allowing him to step through so long as the cat is somewhere in a fairly open space.

There is a reason why 1e described how many Montaigne nobles had been using trapped Mirror ghosts as decoration for their estates, not only are they a nice conversation starter, but they're an excellent defense against any Porte their rivals might use against them.

I am left worried about the hero that kidnaps nobles to steal their Porté... what happened with that? What paths/solutions have you found to said plan? Did he join the Dark Side?

More than one person talked about "the Montaigne book" is this something I should have avalible to me right now as a backer?

You should have received a mail way back in the beginning telling you all 1st Edition books were available for you to download at DriveThrough RPG. There you'll find it. Had you not received such mail,  write to John and ask about it.

The way I see it, Porte is a socery who's usefullness is based on scale. On a single individual looking to use it in combat, congrats, he has his weapon. But it can be scaled up to be useful on a macro scale so easy. Instant armies, instant comunication (compared to everry other method), massively shotened travel times. Porte is powerful for economic and social areas of life, but is near useless for combat, except for escaping.