On the HUD in Splatterhouse (2010), one of the attachments is the Necro Meter. It is the thicker red and white bar attached to the Terror Mask.

As Rick Taylor kills creatures, he absorbs blood. Blood can be used for the four basic Terror Mask abilities: Splatter Siphon, Splatter Slash, Splatter Smash and Beserker Mode.

Using these abilities will use some blood inside of the Necro Meter.