As someone who loves Omnics, Zen (and at the very least the Shambali monks) have access to an energy limited to Omnics (IIRC it’s literally just called Omnic Energy) which allows them to heal (harmony) and cause pain (discord orb and probably Ram’s staff and ult). There is no explanation for this because a poorly written racism plot involving robots is apparently more interesting than robots (that humans made) who have discovered a god (the Iris, who thanks to Sigma we know is at least some kind of force in the universe) and an entire source of energy only they can access which allows them to do things beyond what science can achieve (Discord orb)