Meet Sweet Craze :3

She's a violent yandere pony who really loves sweets X)

Craze is actually a lustful ghost, a spirit who puts on the physical form of a young adult, who haunts an abandoned school, and targets those she takes an interest in…

Her way of operating, is to act like an innocent, friendly girl from another school, who then starts to flirt and obsess over any pony that she finds. Soon she starts to get more clingy to them, and then starts to make other ponies who are close to her obsession "disappear".

Then once she has them all to herself, she makes sure that they die by her hoof, so that no one else will be able to try to love and "steal" her lover. And then after that, she moves on to her next victim…

No one knows she's a ghost, nor do they wonder where this school of hers is supposedly. And those who do know about her true nature?
it's already too late for them…

Some say she is like this due to her past life, obsessing other another schoolmate and dying in the process of trying to claim them as her own. Once her previous lover moved on in life, she then became a ghost, trying to reclaim that love.

It should be noted that Craze is a sweet tooth, as offerings of candy and sugary goods are enough to distract her or tempt her to do something.