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.
- The Lord of the Rings: The One Ring can only be destroyed in the same place where it was forged, in the fires of Sammath Naur in Mount Doom.
- In the Redwall prequel Mossflower, Boar the Fighter reforges Martin's sword from Thunderbolt Iron in his forge atop the extinct volcano Salamandastron.
Live Action TV:
- Star Trek: Deep Space Nine: According to a legend related in "The Sword of Kahless", the ancient Klingon Emperor Kahless the Unforgettable forged the eponymous first-ever bat'leth by drawing it from the fires of the Kri'stak volcano.
- 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 millenia old.
- 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).
- The Elder Scrolls V: Skyrim
- The Skyforge is the only place where Ancient Nord Armor and weapons can be made, and it's the only place where Skyforge Steel weapons can be bought.
- The Dawnguard DLC adds a quest "Lost to The Ages" in which your character finds four shards of the incredibly rare material Aetherium, and the legendary Aetherium Forge which is used to turn them into a unique item.
- The Witcher 3: Wild Hunt: Jonna and Fergus' forge at the Crow's Perch is the only place in the entire game that crafts master-level armor such as the Witcher armors. Hattori's forge in Novigrad is the only place that forges master-level weaponry such as the Witcher blades. Both forges are only available after you complete the multi-point quests which can only be started when you've leveled your character up high enough.
- World of Warcraft:
- In vanilla, Dark Iron can only be smelted in the heart of the subterranean dwarven city, Blackrock Depths.
- In the Legion expansion, Demonsteel can only be made in one special anvil, high above the tallest mountain in the continent.
- There's even a non-metallurgical example: various types of magic cloth can only be produced once per day in various obscure elven locations.
- Classic alchemy flasks could only be made at alchemy labs, which only existed deep in 2 endgame dungeons.
- 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 Roseís sword and all the Crystal Gemsí other non-summoned weapons.