The Ultimate Forge is the only place in the world where the Sword of Plot Advancement or Armor of Invincibility can be made. It's invariably very difficult to reach, atop the highest mountain or above a river of lava. Just what makes this forge so special may never quite be explained, but it's safe to say that either magic or Lost Technology is involved. The Ultimate Blacksmith might hang out here, but it's also common for the Ultimate Forge to be abandoned or guarded by monsters.
Compare Eye of Newt.
- Marvel Cinematic Universe: Nidavellir, realm of the Dwarves, is a Ring World Planet surrounding a neutron star. By drawing power from this star, the Dwarves are able to forge the strongest weapons in all of existence, including but not limited to Thor's hammer Mjolnir. Before Avengers: Infinity War, Thanos forced the Dwarves to create his Infinity Gauntlet under the threat of death, and then froze Nidavellir's star to prevent anyone from creating any weapons to counter it. Thor, Rocket, and Groot, however, are able to revive the star long enough to forge Stormbreaker, an axe powerful enough to kill Thanos.
- Dungeons & Dragons 2nd Edition Book of Artifacts. Long ago the First King of the dwarves created the Anvil of Songs, one of the five Great Tools. He then used the Anvil to create the fifth Great Tool, the Fierce Axe, which later became known as the Axe of the Dwarvish Lords.
- Warhammer 40,000: Forge Worlds are planet-spanning factories that churn out mind-boggling quantities of weapons, equipment, and vehicles for the Imperium of Man, headed by a Fabricator-General of the Adeptus Mechanicus, and often containing utterly irreplaceable manufacturing facilities and jealously-guarded STCs for designs ten millennia old.
- The Elder Scrolls V: Skyrim
- The Skyforge is a structure beneath the stone wings of a great eagle statue, said to be older than the elves, and when discovered by some ancient Nord heroes, they decided to build the mead-hall of Jorrvaskr next to it. The Skyforge Steel weapons it produces are superior to normal steel equipment, and after the Companions questline is completed it can also produce Ancient Nord Armor and Nord Hero Weapons. While the resident blacksmith Eorlund Gray-Mane is considered to be Skyrim's Ultimate Blacksmith, some of his rivals in other cities may grumble that they don't have the advantage of a legendary forge to work in.
- The Dawnguard DLC adds a quest "Lost to The Ages" in which your character finds a shard of the incredibly rare material Aetherium. This prompts a quest to hunt down three other shards and team up with the ghost of an adventurer to find the legendary Aetherium Forge and create a unique item.
- Golden Sun: The Lost Age
- The game has one, but it's not the Ultimate Blacksmith's residence (he lives in Yallam, a backwater-by-backwater-standards). Obaba's forge is located in Champa, and consists of a huge hole in the ground deep enough to reach magma. She uses it it reforge the broken trident and give her pet salamander a huge power boost when she still thinks you're the bad guys.
- In Dark Dawn, Obaba is still in Champa despite it being overrun by the shadow monsters, kept at bay by burning any wood the inhabitants can get their hands on. She now serves as the Ultimate Blacksmith (many other world locations having been fundamentally changed or removed in the thirty-year Sequel Gap).
- World of Warcraft:
- In the classic game, Dark Iron can only be smelted in the heart of the subterranean dwarven city, Blackrock Depths. Which is to say, near the end of an enormous dungeon.
- In the Legion expansion, Demonsteel can only be made in one special anvil, high above the tallest mountain in the continent.
- Non-metallurgical items get in on this as well. In the classic game, alchemy flasks could only be made at alchemy labs, which only existed deep in two endgame dungeons. And Mooncloth used by tailors can only be created by purifying Felcloth in night elven Moonwells, and for nine years you could only create one sheet per day.
- Whateley Universe: Eldritch, an Artificer who had just recently liberated herself from the risk of being magically enslaved, found an abandoned Artificer forge left over from Five Courts era, in a hidden cave under Uluru. Realizing that a malevolent force had awakened it, disrupting the Ley Lines near the mountain, she destroyed it to keep it out of the hands (tentacles?) of the Eldritch Abominations that were trying to corrupt it.
- Atop the Fourth Wall: Linkara's ship Comicron 1 (which he took from Lord Vyce after defeating him) is revealed to have a program he calls "The Forge" which can draw matter from other dimensions and use it to instantaneously fabricate materials. While primarily used to make shades and weapons, it can also immediately repair the badly damaged ship after Vyce unlocks the function, in fact it's the only thing that can repair the ship as it was made with substances from other universes.
- Steven Universe: Bismuth has an elaborate, apparently magma-powered forge hidden in a volcano, which she used to make Roses sword and all the Crystal Gems other non-summoned weapons.