Life Force

Life Force is a concept introduced in Phantom Hourglass, but has technically been in every game so far. Life Force is pretty much anyone's health, such as Link's hearts. In Phantom Hourglass, it is revealed that Bellum, the main antagonist of the game, starts draining all the life force, and Oshus, the Ocean King, attempted to stop it, but failed. Bellum traps Oshus at the bottom of the Temple of the Ocean King, which continually drains the life force from him, and anyone else who enters. Bellum crystallizes this life force to create the Sand of Hours and uses this sand to create the various monsters and bosses that cover the land and sea. The monsters then become tools for gathering others' life force. Bellum also creates the Ghost Ship to lure unsuspecting victims to steal their life force as well.