From Diablo Wiki
Portals are found in red and blue varieties, but they have the same function. Each type instantly transports a character from the portal to a remote location.
Blue portals are most often Town Portals, cast by characters from town portal scrolls or books. These must be purchased or scrounged up from monster drops; the skill can not be learned in Diablo II as it could in Diablo. Blue portals are also created by Portal Shrines.
Red portals are special types of portals that transport characters somewhere other than town. They are usually cast by NPCs or found at pre-existing transportation points. A complete listing of these can be found further down this page.
Casting a town portal instantly opens a portal to the town in that act. Each town has an area where the portals appear, and it's possible to tell the portals apart since the hover text on each says where they go, and which character cast them. This is not the case in single player games, and if a character casts a portal on the same level as a Portal Shrine was activated on, there is no way to tell which portal is which. Portals created by Portal Shrines remain open for the duration of that game, no matter how often they are used.
Returning to the dungeon through a town portal cast by your character will immediately close that portal. Casting a new town portal will close the previous portal cast by that character, if it remains open. (Even if that previous portal was in another act.) A character who goes hostile will see their portal close instantly. Even though hostile characters can not move through portals, they can see who cast them and where they are; keep this in mind if you are in the dungeon and there is a hostile player in town; your portal will give away your location, and if you are near a waypoint, this can be a dangerous problem.
Only the character who cast a portal, or other characters in her party, can use her portal. Since portals only close when their caster uses them to return to the dungeons from town, other players in a party can make an infinite number of trips to and from town through another character's portal. Be careful not to remain in town when the character who cast the portal returns, or their portal will vanish and you will have no way to get back to the battle (short of asking one of the characters there for a portal.)
Portal TipsDiablo all along the River of Fire causeway, or down to Baal from the Worldstone Keep level 2 is no fun at all, especially if you didn't clear those levels the first time, and it's impossible to kill the monsters blocking your path back to your corpse.
Town portals are useful ways to escape trouble, whether from monsters or from other characters. Bear in mind that town portals are not Recall spells, as seen in some games. Your character must have space and time to cast the spell, and then be able to walk through it. This may be impossible in a hurry, or when mobbed by enemies.
Use town portals to save time while exploring areas. If you're looking for a waypoint, and you find the stairs to the next level first, or to some dungeon area (such as the Maggot Lair), cast a portal by the stairs, continue looking for the waypoint, and when you find it take it to town, then return through your portal. Don't forget you've got a shortcut portal waiting and cast another one in some distant corner of the level, though.
This technique can be expanded upon when playing in parties; one character can cast a portal somewhere, such as at the entrance to the Frozen River, and then once the level is cleared and Anya is rescued, a second player can cast the portal to return to town, before everyone goes back through the first portal to resume exploring the Crystalline Passage.
After v1.09, portals can not be used to skip to areas late in a quest, if this will take a character past one of the "blocking quests." This feature was added to make rushing low level characters through the game a bit more difficult, so it's no longer possible to simply arrive in Lut Gholein, take a friend's portal to the Canyon of the Magi, and tag along while they find the true tomb and kill Duriel for you in 3 minutes.
Levels that can not be portaled to until the previous, required quests have been completed include:
- Act Two: The Harem, Palace Basement, Arcane Sanctuary, and the Canyon of the Magi, Seven Tombs of Tal Rasha, and Duriel's Lair.
- Act Three: Durance of Hate 3. (Portals may be taken to Durance of Hate 2, to get the waypoint.)
- Act Five: The Arreat Plateau, or the Worldstone Keep.
Red portals work just the same as blue ones, transporting characters who walk through them to different locations. These are usually found in the dungeons in a few set places, or created by NPCs. They never take a character back to town, and instead bridge different locations. Anya casts one to let players persue Pindleskin. Tyrael casts one for players to exit the game through once Baal has been defeated. And so forth.
A complete list of these can be found below.
A complete listing of all the special portals in the game, red or blue. Not included are Portal Shrines, which can appear on nearly every level.
- Red Portal from the Field of Stones to Tristram, as part of the Rescue Cain quest.
- Cain's "NPC-only" blue town portal he opens once rescued in Tristram.
- A portal shrine style (permanent) town portal appears on level 4 of the Catacombs, after Andariel's death.
- Players use the cube recipe to open a red portal to the not-so Secret Cow Level.
- A blue portal appears in the magical archway that conveys players from the Palace to the Arcane Sanctuary.
- A red portal appears in the Arcane Sanctuary after The Summoner's death. It takes players to the Canyon of the Magi.
- Tyrael opens a town portal from Tal Rasha's tomb back to town.
- A portal appears in the Hell Gate on level 3 of the Durance of Hate, after Mephisto is killed. Players use it to advance to the Pandemonium Fortress in Act Four.
- In the expansion, Tyrael casts a portal in town that takes players on to Harrogath in Act Five, after they have defeated Diablo.
- The three groups of imprisoned Barbarian NPCs cast their own "NPC-only" portals when rescued.
- There are three red portals in the surface areas that take you down to special River of Flame areas.
- Anya casts a town portal only she can use to return to town once she's freed from her Prison of Ice.
- Anya casts a red portal in town to let players advance to Pindleskin's Zombie Garden.
- Baal creates a red portal to travel from the Throneroom to the Worldstone.
- Tyrael casts a red portal after you kill Baal. Traveling through this one exits a player from the game and brings up the congratulation/title screen.