The Mad Hatter’s Fear Toxin - Batman: Arkham Unhinged

Originally developed and manufactured by The Scarecrow, aka Professor Jonathan Crane, the former neuroscientist Jervis Tetch altered this new strain of Fear Toxin to force the victims to undergo vivid hallucinations of a Wonderland-like environment. He used various props and costumes to sell this nightmare further. 

It was used against Batman when the hero stormed his shop in search of the kidnapped Vicki Vale and Pamela Isley. While it initially weakened him, he was eventually able to overcome the toxin’s effects, taking down the Hatter once and for all. 

After the adrenaline in his system subsided, he was able to administer an antidote that could neutralise the effects of the drug.