He first appeared in-game during a short battle in Mount Hyjal, where he led the assault on Malfurion's base. After his defeat, Rhyolith made his escape back to the Firelands.
Rhyolith made his next appearance during the battle at the Molten Front, where he rallied his master's forces to fight against Malfurion's armies, who were in the process of planting a tree within the Firelands itself.
He made his next, and final, appearance during the final assault upon the Firelands. The army that faced him in battle utterly destroyed his armor, allowing them to harm him. In the end, Rhyolith was slain once and for all.