Obsidian

is a material that comes from the Obsidian Shards that fell from the sky when the moons collided during the Cataclysm. This material has magical properties that the Cabal of Obsidians used to power their magic.


 * The power of the Obsidian Cabal sprang from the shardstone that fell from the sky, and nowhere was it more concentrated and potent than here in Desolis.

Some creatures exist that are made out of pure such as the Obsidian Golem. These creatures are immune to magic attacks.

The magic school of Chaos exclusively utilizes small fragments of this material, known as Obsidian Chip for a reagent for this school.

Lore
“I told you, Aren, everything has its opposite. As I represent the ancient Virtues, the magic of the shard represents dominion. You must destroy it or the Virtues will have no space to take hold, no room to grow.” “All right,” Aren said with a sigh. “How do I destroy magic purpose?” “By destroying the great shards,” she said. “There are two: one in the place where the rivers cross, and the other in the seat of Obsidian power.”

Trivia

 * Obsidian seems to be fragments of the shattered moons caused by the Cataclysm, and not related to obsidian glass. It shares many properties with Blackrock in the Ultima series.
 * Obsidian may be named after the Obsidian Order, or vice versa.