Tox-En


 * Tox-En is a form of Energon.

Tox-En is a highly poisonous Energon variant, easily identified by its sickly green color and visible fumes. It has the opposite effect as regular Energon on Transformers, causing them to feel nauseous and weakened by the slightest physical contact. Prolonged exposure to Tox-En can outright paralyze a Transformer, eventually extinguishing their spark.

Needless to say, it's pretty nasty stuff which sane individuals will dispose of on sight. In the hands of a complete lunatic, however, it can become a devastating weapon against their enemies.

Prime cartoon
Megatron found a way to refine raw Tox-En during the war, converting it into a bioweapon that devastated the Autobots. A sample of the substance came into Autobot possession and was stored in the Vaults of Iacon.