Nu's possession

The awakening of Nu's power within the Chalise, allowed the cruelty and malevolence grow within whomever drank from the chalice. in time, with enough negative Ka, the person would transform and with the chalice, become Nu reborn. instead of a single target who drank from the chalice becoming possessed, the town had the misfortune of being the starting target of Nu's monstrous power. There was enough negative Ka from the greed and gluttony from all the merchants and people living in Heracleion to manifest Nu's power and bind all those living there to the curse. Not enough to remake the primordial god, but something in between