Nefasturris is the boss for Mission 6 of Dante's Disc. This is the only fight in the game where it is completely consistent as long as the player preforms the set up correctly.
This fight has evolved it's strategy throughout the years when DMC2 speedrun scene was still at growing phase. Varying from S rank on demand with Million Stab then Round Trip for faster phase 2. Eventually Radge made consistent Majin set up for this fight which LonerHero optimized the usage of it on phase 2.
In Phase 2, it's decapitated head continues to fight as Nefascapitis. This phase can be very dangerous to fight it head on head.
NG+ Note: Round Trip is used against phase 1. Phase 2 can be done the same, but stronger and more consistent alternative is Quick Heart + High Time spam.
NG+ Phase 2 example. This is NTSC version, where offence heart and sword damage are bugged.
If you fail to set up Majin, then you will lose significant amount of time in Phase 2. You must get hit by the Giant Laser 3 times then tank the 4th hit with DT.
The speed of this fight depends on how well you can Shotgun Cancel at Phase 1. It is important to conserve enough DT gauge for the optimal cycle in Phase 2. As a result, these are important scenarios to keep in mind for Phase 1 :
Full Fight Demo
Only consider this option if you shoot more than 3 Fireballs.
For some reason, Doomsday forces Nefascapitis to stop floating. This gives you enough space to finish it off without losing too much time.
If you are playing NTSC version, you can take advantage of Continuous Doomsday glitch.