Is there a spell that enables one to create a portal? If not, how are portals created? Are there different skill levels needed to create portals that are:
1. Two-way
2. One-way
3. Obscured
4. Transparent
5. Etc.
Where are the official WotC rules on portal creation?
Planescape has always been weird with portals. it explicitely states that there is no way for a mortal to create a permanent portal, and yet we are constantly running into portals that seem to have been specially designed to fit a mortal agenda. I like to say that this is simply because people build their fortresses on top of portals, but sometimes it's just so blatant (like the perfectly placed portals to the quasi-elemental planes in the Armory) that one must turn to the vagueries of belief or manipulations of the powers for an explanation.
But yeah, the important part isn't that there is no way to create a permanent portal, it's that there is no way for a PC to create a permanent portal.
Well, exemplars ain't mortals. It's not so hard to think that exemplars can't make portals.
Or maybe there's only one kind of exemplar that knows how to make portals, and its the Rilmani. The entire system of so called 'natural' portals is made to balance out flows of alignment tainted belief throughout the planes. Which also explains what your have different types of portals. Sometimes to balance out the flow of belief to different areas, you need to have it go one way.
It's not like the Rilmani don't have the ability to infiltrate these areas or the mysterious motives to do so.
Per the FRCS, you must be at least 17th level, know the specific feat to create portals, be able to cast either teleportation circle or gate, have visited the places where the portal leads at least once (and not have at least one of them blocked to Astral travel) and need a permission slip signed by your mother, your cohort's mother, and your fifth-grade teacher.
It all makes sense now.
In my Planescape campaign, it's only NPC's and Powers who are creating portals. I just wanted to know the rules in case a player asked about them.
Thanks much!
From the Manual of the Planes (pg. 21, 22)
-420
That's not Planescape canon though. Also, even if a gate spell were to be made permanent, it wouldn't be the same as a true permanent portal as portals can be sealed but not dispelled outright. Frankly, permanent portals are sort of a cool idea, but there's a reason they've always been kept out of the hands of the players.
If powerful spellcasters and psions can create entire demiplanes, I think it's not outrageous to let them make portals as well. It doesn't seem game-breaking to me to allow 17th level casters to do so on occasion - if they end up giving Sigil some small competition, so much the better.
The rules for creating portals is also in the Stronghold Builder's Guidebook, page 50. Besides the mages of Toril, there are many mortal spellcasters on Oerth who have constructed permanent portals (for example, the portal to Mitrik beneath the city of Irongate).
A portal that requires a key is the same cost to make as one that doesn't. A two-way portal is really a matched set of one-way portals.
Really the only important point to make with portal creation is that they can't *make* a portal to Sigil. There's plenty of *other* portals out there - so I'd be fine with letting a high level caster make one. 
Clueless wrote:
True, since Sigil portals are created and maintained by Lady of Pain it is logical to assume that Sigil portals are uniqe and diferent than portals created by Powers or high lewel wizards.
Also, I think that since Sigil portals are most common in multiverse, it is easier to find portal to Sigil, then there find portal for your destination than spend god knows what resourses to create your own.
In short: Create Portal feat from FRCS is OK, but is not worth hawing (at least not to PC).
I don't know who would want to make a portal, you never know what pesky adventurers will come through (pun intended 
).
The problem with making portals is like most enchanting and cursing problems, you never know when it will fall into wrong hands(tentacles...) or if the enchantment turns back on you.
Making a portal is like inviting danger to your doorstep and it is even problematic when you only use it to pick up groceries (anybody watched or read "Howl's Moving Castle").
On the other hand destroying portal is as risky as creating one.
I think that there shouldn't be any rule against letting a sufficiently high-level PC create any type of portal he wants, given a couple of limitations. Basically if a high-level caster/psionicist can make his own freaking demiplane I would hope that he had some way of creating a portal to it, too. Who wants to travel into the border Etherial and then Deep Etherial every time you want to visit your summer home?
The limitations should be that it's expensive to create permanent portals, and while I can't see why a wizard can't create a keyed portal, I can see there being a restriction on where the "other end" of the portal comes out. You can't just link your home with the Council of Law in Automatia because you don't own that end or have control over it, and you can't just create a portal from your demi-plane (or any plane) and Sigil. Only the lady makes portals in Sigil....or at least only she allows the portals that exist there. Making a permanent portal between two sites such as Faunel and the Plain of Infinate Portals may be important to a pc group, but may not be defended easily and even may not remain under the maker's control. So basically you've got a ton of wasted jink AND xp because the lizard lord decided to call kip in your portal tree-branches .
Portals and gates aren't "hard" magic. Making a +3 sword isn't "hard" magic, either. But neither one is cheap or quick or worth the trouble all the time.
In the first adventure of Well of Worlds the characters can explore an artificial portal to Baator. That book is official, therefore I see no problem in using the portal creation rules from the FRCS, too.
The only rules I know of for portal creation come from the 3e Forgotten Realms Campaign Setting. In Planescape, there is no way to create a permanent portal, although certain spells such as 'gate' can achieve a temporary one.
From a planar perspective, the bloods in Faerun have found a way to create portals, but then again, the entire world is odd. Let them try pulling that trick in the planes and see how far it'll get them.