Crane instead gasses him with the fear toxin, leaving him in a state of psychosis.
However, he also conducts experiments on his patients, using a fear toxin developed with Ra's al Ghul to break their minds.
The Scarecrow then experiments on him with fear toxins.
Batman (who was under the influence of Scarecrow's fear toxin) experiences flashbacks of his parents' murder.
It is then revealed that the entire episode was merely Barbara's nightmare, induced by the Scarecrow's fear toxin.
Through the use of his fear toxin, he resurrects the Joker as a hallucination in Batman's mind.
He is defeated by Batman and Robin before he can realize the final stage of his plan: to use fear toxin on an entire stadium.
He will poison the player with his fear toxins, take a gigantic appearance, beats up the opponent before sending the player into the next arena.
He would return as a hallucination in Batman's mind caused by the Scarecrow's fear toxin.
Aquaman is rendered aquaphobic due to an altered form of the Scarecrow's fear toxin.
