Transmutation is an underrated power that I don't see talked about much around here. It's applications are diverse and have solid foundations for those who like to rely on real-world science to "explain" or make sense for the power. You see, at a glance it might even be a little difficult to think of an attractive use for this power, also because people here opt for things of omnipotence, but Transmutation is very useful and applicable, you can transmute practically everything, since everything is matter and energy, and everything is made up of atomic and subatomic particles, molecules, cells, etc. All of this can be changed, rearranged, reconfigured or transformed. Which means you can simulate both the creation and destruction of matter. You can transmute air molecules to "create" matter from "nothing" or the opposite by transforming matter into air (oxygen) to "destroy". From there the sky is the limit. Even immortality, as you could transmute your own cells into new ones, strengthen your body and all that. Imagination and creativity is the real limit, because in nature nothing is created and nothing is destroyed, everything is transformed, and that's what this power does.
And for those of you who like to be science-based, this power is basically Strong Nuclear Force, or an application of Nuclear Manipulation. Nuclear Transmutation already exists in the real world, despite being very difficult and limited to experience.