LORE: Every "magical" class has a source of their power, what is Monk's source of power?

It’s literally life magic.

Mistweavers could be said to ctually being using the water portion of shamanistic power, except more exact, where as shamans kinda drop a bucket on their target, monks trace a few drops into whatever they need to effect.

Monks are the closest thing WoW has to water benders. And I mean literally water benders, as weaving it in and around is literally bending it.

Literally.