This level kick starts straight into a boss battle with Nefasturris popping out of a building. It shoots powerful beams from its mouth that is either in a single horizontal sweep or multiple smaller beams exploding outwards. Because of the debris he is leaning over on, it is difficult to use melee tactics initially which leads you to use your guns. Eventually, it will send out Nefasvermis during the fight to block your attacks; simply shoot them out of your way. The beams sweeping from left to right often range at 3 heights (ground, medium, and high) as well as a beam that will follow to whatever height that Dante is at; just evade these by dodging in the opposite direction it is sweeping. With the explosion attack, jump in the middle of the explosion where there are no beams shooting or dodge away.
When you finish the first part, Nefasturris will shoot out its head and turn into Nefascapitas. It uses the previous explosion move, expels “clouds of energy”, and finally strings of lasers much like Griffon did. When it becomes stationary, hack away at the remaining length of spine behind him which is its weak point until he dies.