Scaldseat

Scaldseat is an underwater volcano off the eastern coast of Issylra not far from the fishing village known as Shorecomb. Within, it holds the Core Anvil, the chambers that once were the domain of Moradin, the All-Hammer.

Description
Scaldseat volcano rises from the ocean depths in a cone shape, forming through many eruptions. In 812 PD, the volcano was still active and, from the surface of the Ozmit Sea, was marked by a column of smoke rising from the water. Around the mouth of Scaldseat, there are multiple vents, sources of lava outflow battling against the ocean water and fume pushing off any of the ocean floor sediment. There is a number of little, pink and purple plant life pulled into the porous rock on the outside of these vents.

The tunnels within it are filled with toxic fumes that deprived the air of oxygen.

The entrance to the Core Anvil is sealed by a wall smoother than the rest in a perfectly square chamber with no sign of a keyhole or handle. There are faint runes or glyphs in celestial that are pressed into the stone and has been untouched for "quite some time". They translate a message: "Here the Crafter's Halls lay dark, the means of making the World Ender gone. Allhammer protect us all." Behind the stone layer, there is a dark metallic surface.

History
Inside the chambers beneath Scaldseat is the Core Anvil which Moradin used to craft his finest creations, including the first dwarves and the Prime Trammels used to banish Tharizdun in the Calamity.

When Vox Machina sought help from the gods to combat Vecna, Ioun taught them the secret of how to craft more Prime Trammels and showed them the location of the Core Anvil. They teleported to Shorecomb, a coastal town five miles from Scaldseat volcano, sailed out on the Shore Shanty, and dove down into the ocean, breathing water via Keyleth's Water Breathing, to reach a small fissure near the volcano, a small air pocket with a bubbling water pool in the center and hot air filled with volcanic fumes that lacked oxygen, suffocating Vox Machina. Vox Machina discerned that they still can breath healthy water and Grog remembered that he has an Alchemy Jug to create freshwater and move it along with the party as an air tank.

Proceeding down the tunnels, Vox Machina fought magma bulettes, entered the Core Anvil, encountered ancient constructs, and crafted three Prime Trammels.