Pool

Brought to the world upon being visited by The Watchers, and originating when Excalibur was pulled from the stone, the energy was sent coursing through the world, with several hyper-focus points.
Most notably, a horse was born in the very spot pool was most focused, leading to it being a reservoir of pool energy.
Pool energy is the single most powerful energy in the world, and was the cause for generations of humans with beyond human abilities.
The key sources for a human to obtain pool related abilities, are either by being in possession of a Pool Artifact, or by having a sexual encounter with The Horse.
The power also just so happens to make you extremely good at playing pool.