According to Advaitins, who set in motion the law of karma?

Is it Saguna Brahman or Nirguna Brahman?

The vyavaharika satya or jagat along with its karma, rebirth etc. is not completely mithya.

When advaitins say it is mithya, they simply mean its not what it seems ... (i.e. this jagat along with its varieties is only nama-rupa, an apparent reality superimposed on the formless brahman).

So in advaita, the jagat is neither completely mithya nor completely true. Its just an apparent, transactional and impermanent reality, and not the ultimate reality.

My point is, if its not totally mithya, then law of karma is also not totally mithya. So who set in motion the law of karma?