User blog comment:Perchan/Slayer Magic Rule Revision/@comment-5497946-20160114224359/@comment-24384232-20160116141301

Gravitons are a theortical particle that might deal with gravity. Beyond that, there is very little scientific evidence to suggest they really exist, as scientists have come up against a giant wall when it comes to quantum physics and in their ability to interpert and explain how it works. We do however know that large bodies of mass have correspondingly large fields of gravity, so going along those lines... if you're character was a gravity dragon slayer, they would likely be forced to consume materials with an extremely high density as to retain a high level of mass themselves.

Still, considering its roots in actual mythology gravity is something that can be manipulated through Darkness Magic, so there you have it.