It is unknown when Jogo was able to develop his Domain Expansion, but he claimed that he utilized his expansion prior to his fight against Satoru Gojo.
The environment constructed by Jogo's Domain is a fully closed-off stone chamber that resembles the inside (or caldera) of an active volcano. Spouts of magma eject from fissures in the ground and walls, and the Domain's ambient heat is such that ordinary sorcerers will burn up immediately upon entry.
As with any Domain Expansion, Iron Coffin Mountain allows all of Jogo's cursed techniques to hit their mark with certainty, as well as greater explosivity. An example of such an auto-hitting attack is the creation of a large, burning rock that instantly appears at the enemy's location.
Jogo's first and only-seen deployment of his Domain came amid his first fight against Gojo, in Jogo's attempt to bypass his foe's infinity using his Domain's cannot-miss attacks. However, dangerous as this Domain is, it was easily outpushed and suppressed by Satoru Gojo's Unlimited Void, showing that Jogo's Domain was far less polished.