Law of Equivalence

The world is governed by an absolute law called the Scales of Equivalence. No one can escape! Every breath you take, every transaction you make, every thought you take leaves a mark. If you give a tael of silver, you must get back the equivalent value; if you inflict harm once, you must repay it with the same amount of flesh and blood! Any "non-equivalent" behavior will be counterattacked by bad luck, and no one can escape!