Hecate's Blessed

Long ago Hecate blessed a group of her most loyal followers with magic. Soon these few became many and they spread around the world, making their own civilizations that were hidden from regular mortals. The wizards and demigods ended up fighting over some trivial thing. This massive war lead the gods to separate the two worlds and erase all mention of the other from their minds. But the Greek and Roman monsters don't know where not to play so these two worlds are crossing yet again. The seven and friends go to Hogwarts undercover to get rid of the monsters and a much larger threat.