A Forge is a volcano that appears to be an important part of the Sburb sessions.
The player living next to the Forge will eventually have to stoke it. The planet of said player seems to be designed so that the Forge will bring about massive planetary change. Karkat, this player is always the Hero of Space who is also the designated frog breeder and will be in the session's Land of X and Frogs.
The forge is involved in the process of Ultimate Alchemy. After the players build up their houses and deploy their grist rigs to empty their planets' hoards into Skaia, . According to Kanaya, this .
Jade lives next to the kids' Forge, as evident by its transition to her planet when she arrived in The Medium. In and the two previous, Dave and Jade are shown to have ignited the volcano, melted the snow, and rescued some frogs colored as the kids' respective text colors. Soon after, Bec Noir is seen teleporting in over the volcano.
Hephaestus, Dave's Denizen, is referred to as the "Lord of the Forge". He tells Davesprite that he can use the Forge to repair any item he requests (and Dave infers that this could be used to repair practically anything). Dave chooses to repair the Caledfwlch which he broke.
The post-scratch kids do not have a forge, as they were destined to participate in a void session.
Kanaya lives next to the trolls' session's Forge, which is buried under the sands of the desert. It was transported to the Land of Rays and Frogs with her when she entered the Medium. According to Karkat, she uses this forge to destroy the Black Queen's ring in order to prevent Jack Noir from using it. Just like Jade's Forge caused the snow to melt on LOFAF, Kanaya's Forge caused the water to drain away. Kanaya expresses frustration at igniting the Forge.
- The requirement of a ring to activate the forge is a reference to The Lord of the Rings, whereupon the One Ring must be cast into a volcano to be destroyed.
- Hephaestus uses a volcano as a forge in Greek mythology.
- Jake's volcano is not a forge, as it was already active and was when he entered.
- There is no Forge in a dead session.