The Vandrogonite Visualiser was a small, hand-held device, covered in a velvety material. It was nominally a catalogue of alien species, allowing an individual to see what they looked like. It was emotionally and electrically powered, allowing it to drain energy from nearby devices and activate based on strong emotions.
As well as this, the Visualiser also had a mind of its own, allowing it to take over the person who tried to use it. It could also physically create the creatures, powering this by strong emotions and the Rift. It was likely created as a terraforming device, meaning it could also modify the environment. The Visualiser could connect to certain types of visual devices, such as cameras and cellphones. Using this method, the creatures could be teleported from once place to another along the signals. The Vandrogonite Visualiser owned by Gareth Portland was also able to connect to the MonstaQuest cards he created, allowing anyone who used them to create monsters whenever there were strong emotions. (PROSE: Pack Animals)
Two Vandrogonite Visualisers were known on Earth, both found in Rhiwbina. One was found by Achenbrite and eventually given to Gareth. The other was found in the possession of a Vandrogon by Torchwood Three, giving it its name.
Using the creatures in the Vandrogonite Visualisers as ideas, Gareth created MonstaQuest. The game became popular, and soon the cards were used in areas of strong emotion, causing the creation of creatures all around Cardiff. He learned of this power eventually, and began using it to his advantage, creating monsters to kill people he hated. As time went on his mind continue to slip, until the Visualiser had taken him over. He tried to get to Millennium Stadium, using the strong emotions of the fans and the television to change the whole world. He was followed by Torchwood Three, after which his creations were stopped by the creations of Toshiko Sato and Captain Jack Harkness killed him. With the death of Gareth, the Visualiser was shut off and all his creations were destroyed. (PROSE: Pack Animals)