Hellmasker is the Level 3 Limit Break for Vincent in Final Fantasy VII. Unlike most other party members, Vincent only has one Limit per Limit Level, but each transformation has two attacks. Transforming makes him stronger and fully restores him, but the downside is that he becomes uncontrollable. Hellmasker transforms Vincent into a slasher horror movie-style masked chainsaw-wielding zombie that has a status ailment attack at his disposal.
Hellmasker is acquired when Vincent's kills 56 enemies after gaining Death Gigas. A good grinding location is the forest in Nibel Area after Mt. Nibel where as many as six enemies (Battery Cap) can appear in a formation. Vincent can easily wipe out groups of them with multi-targeting E.Skills. The area is available very soon after Vincent can be recruited.
Transforming into Hellmasker increases Vincent's Defense and MDefense by 50%. While in Hellmasker form, Vincent will attack with either Splattercombo or Nightmare, and cannot be controlled. He stays that way until the battle is over, or he falls into Death status. During his transformation, Vincent is immune to Berserk, Frog, and Confusion. The offensive properties of Elemental or Added Effect do not carry over to his Hellmasker form, but defensive Materia set-ups continue to work. Vincent's Limit Break forms behave oddly under All Lucky 7s since he seems to revert to using his gun though there is no animation for it.
Splattercombo is a physical attack for half damage to five random targets. Vincent will use this attack 70% of the time.
As there is no way to control Vincent during his Hellmasker form, there is no way to prevent him from wasting his turn using the status attack on enemies that are immune. This makes Hellmasker perhaps a less useful Limit than his previous Galian Beast and Death Gigas, who can deal damage every turn as long as the enemy does not nullify/absorb their element. As opposed to simply dealing damage, the player can also use Vincent's Limits to heal him, and but Hellmasker does not increase his max health, unlike his previous transformations. As Hellmasker also takes longer to charge due to being Limit Level 3, it seems altogether less attractive than his previous forms. Though it is a unique Limit in being able to inflict ailments onto enemies, the player also has other means to do so, such as Hades and Bad Breath, though they may need to go out of their way to acquire these.
None of Vincent's Limit Break transformations have victory poses, and will continue to use their battle animation after a victory.