Mc comes back after his death in same world quite a bit of time later a cultivator type world where he was the most powerful. one of the people he use to know takes him in a short old man and mc kills alot in later chapters he helped the king at some point and knows how to make pills and has long white hair and he plays a music instrument similar to a koto in early chapters he enters the dream of another reincarnated when he sleeps I think it has to do with a necklace he wears or something
-Edit- found it above all gods

The Blood Reaper