Hermes portal question

In the AM5 rulebook on page 156 there is a spell called Hermes Portal. It has the range: ARC and duration Year. Now there is another spell called Conjuring the Mystic Tower on page 153 of the same book, however this spells duration is Mom meaning that it is forever.
How come the portal only lasts one year when a tower can be permanent even if the portal has a higher level. I know both are ritual spells and that the portal is of Mercurian origin. But shouldnt the Portal be permanent too?

The key difference is that Conjuring the Mystic Tower is a momentary effect that creates a real, non-magical stone tower instantly (this is a special effect - See page 112, second paragraph of the description for the "Momentary" duration.

By contrast, Hermes' Portal is a continuous magical effect with the longest duration available with vanilla hermetic magic. That said, I must admit I'm not sure why the portals aren't simply created as Invested Devices - Perhaps the Cult of Mercury didn't have the capacity to enchant items in such a manner?

Out of game context - travel spells are always a high level in the core rules. THe Portal being forever in previous editions also meant you had things like the Jerbiton Network, which connected about 12 of the biggest cities in Europe, and the Redcap Network which connected all of the biggest covenants in Europe, well, historically important ones anyway, and the Tremere Network, and who knows what they were doing..

I*f the Portal is forever, why aren't there already dozens of them? 15 pawns of vis is a lot, sure...but it's a Stargate!

True there would be a lot of them, but still there would be the problem of logistics... Making two rituals at the same time with an arcane connection to the other place so it is 30 pawns of vis. Plus the space needed for the portals. And what covenant would want some non ally covenant have a portal right into their covenant.
Wasnt there a vis cost for traveling through the portal in the earlier editions of the spell?

I guess I could always make a houserule that makes the spell level 80, permantent and then require that there was a special oil smeared over the portal each year to maintain the connection. But I was more curious as to why the portal was level 65 and the tower level 35. I know there is some extra magic needed to allow people travel through the portals, but still a tower is (or can be) an intricate structure.

[sarcasm]Best thing? The Mercere got them back![/sarcasm]

The reason is that its a Level 75 effect, base. Add in a plus 5 for "constant effect" or a plus 10 for unlimited and you're looking at 80-85 levels of spell. That's a Level 80-85 Rego Terram effect. Then you need to add in levels for size. It would need to be an attuned item. You'd likely need to have a + 10 for runes. By the end of things, you're looking at up to 100 levels of spells. Also, the spell is 1.) a ritual and 2.) pre-Hermetic, making it even more sketchy to instill into an item. You might be able to pull it off if you had Hermetic Architecture.

But frankly, there's a far, far more efficient way to do this. Leap of Homecoming is a Level 35 Base. Add + 5 for touch, and you can instill it into an item. Like a stone or metal tablet one stands on. Spend a few seasons making these, and binding them by arcane connections. Now its a Level 40 + 10 Unlimited for a Level 50 effect. A specialised Verditus could create one of these in two seasons (one to open, one to enchant, if you assume a 40 point lab total pre arts (not unheard of), and level 20 Rego and Corpus each, with Elder Runes. Then you have a lab text and churn them out like Godiva chocolates. You could also create an effect for Rego Herbam and send things through in wooden crates (using the same premise that lets Leap of Homecoming carry one's possessions with one), so long as the contents weigh no less than a human, you could ship through just about anything.

Best part, the leap of homecoming thing only costs you 6 pawns per tablet, 1 to open the devise (with appropriate craft score) and 5 to enchant. Way, way more reasonable than the up to 10 for the Portal of Hermes madness. And no hand-wringing about transfering a non-hermetic ritual into an effect, breaking a whole tonne of rules for such things.

Plus, you can activate the effect by saying "beam me up, Scotty."

The invested device version is definitely hitting the target with a spell of sufficient mag. to induce warping. Leap as a spell (or personal invested device) skirts that by the 'own/designed for self' rule. Anyone else would score 1 warping point per use. Ouch.

The Hermes Portal by comparison is an enchantment on the portal, not the traveller. Thus I see it being a preferable option for travellers.

As for there being a network already, personally I think that is cool. The covenant major hook 'road' may mean exactly this - sure you get a portal, but any such would come with baggage and expectations by non-covenant magi. It also means much more frequent redcap and quaesitor visits - not always a good thing!

That is explained in HoH-TL p. 80. Basically, Mercere did figure out how to enchant items as permanent portals, but the secret died with him. His descendants have managed to copy the portals themselves, but not to figure how to modify the effects, and even building them is still a secret of the House. The rules for portals as invested devices are in HoH-TL, p.100. You need to construct two portal items (ReTe 65) then perform a ritual simultaneously at both locations (ReTe 75). And then the portal can't be moved without destroying the effect.

So the Order has a ritual spell that is not fully integrated with Hermetic theory, and the Merceres know how to make invested devices by copying the existing ones but don't understand them fully. Oh, and after the Diedne wars many of the portals that did exist were shut down because they were considered too much of a risk.