The Butterfly Effect... in Overlord.  Nigun's final effort here was not 'an angel' but rather a spell that had an unexpected side effect.  Ainz is given a human body.  From here, he must navigate his choices with his human mind and emotions intact.  Does he tell the guardians, if so, when?  Who?  How?  What choices differ when he has human wants and needs, and where does he go from here?  Read on to find out, but know this... whatever his form, where he goes, the world will follow, whether it wants to... or not.