Cetus

Foundation finds island completely devoid of life. Either in Mediterranean or mid Atlantic, idk yet. Step foot on island, you die. Due to 0 E.V.E, island serves as EVE vacuum. any EVE is immediately drawn to the island and dissipated across it. as life runs on EVE, it instantly kills anything that steps foot on the island. once foundation develops suit to prevent this from happening, they explore island. some very very destroyed ruins of what seems to be an ancient city, but so little of it remains it's hard to tell. they find a hatch that leads to an underground structure, where they find a massive eigenweapon. find ancient manuscripts that detail an ancient civilization that existed on this island, they were the pinnacle of local civilization. one day, boats begin to vanish. investigation reveals that there's a massive sea monster in the waters around the island that's purposely attacking them. they try to use their standard magical weaponry, but nothing works against it. the monster, the Grand Beast Cetus, claims to have been sent by the gods, specifically the goddess Cetos, to exterminate the civilization, as they were becoming callous and abusive to the nature around them. the city scoffs at this and continues their attempts to terminate Grand Beast Cetus. eventually, they manage to capture it and bring it to the underground structure. they keep trying to terminate it to no avail, as the Grand Beast continues preaching about how it has been sent on a divine mission to dispense judgement. it eventually escapes, after which the city delves into the magic of others to find a way to destroy it. eventually they develop the eigenweapon and fire it on Cetus. the manuscripts are purposefully vague on whether or not the eigenweapon worked on Cetus, but they do say that it stopped bothering them. but the manuscripts continue, detailing how after the eigenweapon was fired life became more and more difficult on the island, as if the island itself was trying to choke them out.