Several of them appeared in Zane's dream.
The Ninja found several deceased mummies of them in coffins In the Ancient Pyramid. When lava rushed into the room they were resurrected as undead mummies. The Ninja fought them and managed to escape. It is unknown what happened to them after the pyramid's destruction.
They traveled with Aspheera and fought the Ninja.
Never Trust a Human (flashback)
The Pyro Destroyers were building the Ancient Pyramid when they spot Wu and Garmadon hiding. They brought them to King Mambo the Fifth, who decided to lock them in a cell.
Legions of them attack the Monastery.
They try to enter the gate to the Underground Base.
Zane gets a flashback about the Pyro Destroyers.
- 99. "Wasted True Potential" (dream)
- 105. "Ninja vs Lava"
- 108. "Ancient History"
- 109. "Never Trust a Human" (flashback)
- 110. "Under Siege"
- 111. "The Explorers Club"
- 112. "Vengeance is Mine!"
- 128. "Awakenings" (flashback)