Gravity engine

The Gravity Engine is a device usable as a defensive weapon, possibly in the sense of "a good offense". It appears to generate a purple aura in the visible spectrum while in use, but no other useful details are available.

The owner, and possible creator, of the Gravity Engine is Yeti of Master Payne's Circus of Adventure. A fair surmise might be made that due to Yeti's size and build, and the name of the invention, the wielder of the Engine needs to be quite sturdy him or herself.

The only time the Gravity Engine has been seen in operation so far was in preparation to fight the Monster Horse Beastie in the Circus's camp while Agatha was still travelling with them.