Tox-En was also the fourth Iacon relic to be found in season 2.
During the Great War, Megatron created Tox-En for his Decepticon chemical warfare to wipe out the Autobots. Bulkhead mentioned that he witnessed an entire unit of his fellow Autobots got wiped out due to exposure of Tox-En unleashed in battle. Sometime, the Autobots managed to capture a chunk of Tox-En and placed it in Iacon on a special containment unit. Bulkhead battled Hardshell and threw the last piece to Hardshell as he fell into a volcano. The Tox-En was extinguished as it melted in the lava inside the volcano.
- Given its color and effect, Tox-En can be though of as a reference to Kryptonite, a weakness to the Man of Steel from the Superman comic books.
- All the other relics were to be used as weapons/tools by the Autobots. Despite being willing to use the Spark Extractor, it is unlikely the Autobots would use the Tox-En. Since Alpha Trion packed the substance, it could be presumed he had a reason, yet it is still unknown.