The Plasmius Maximus is a device designed by Vlad Plasmius that short-circuits ghost powers for three hours. When shocked by it, Danny and Vlad cannot transform into their ghost halves for the duration of its effects. Ironically it also allows Danny to be immune to the Fenton Spector Deflector effects after he is shocked by it.
In "Maternal Instinct," Vlad uses the Plasmius Maximus on Danny in his Colorado chalet, effectively taking away his ghost powers for three hours until midnight. Vlad then sends his experimental "pets" to chase a human Danny through the woods.
Later, at the end of the episode, Danny uses the device on Vlad after he claims that he's still more powerful than his pets even with the Specter Deflector on. This takes away Vlad's ghost powers, and Danny sends his pets after him much as he did earlier to Danny. It unknown what happened to the device after but it is likely Danny kept it or destroyed it.
The Plasmius Maximus is a small, handheld device. It's made of silver metal and has a handle connected to a small, square section with a screen on it with green lines against a black background. Coming out the front of it are two glowing green prongs used to shock the target on contact.
- 117. "Maternal Instinct"