Mundus' Spawn is a boss in Mission 14 and has two separate health bars One is for Mundus' Spawn, and the other is for the mother, Lilith. This fight is one of the most decisive point in the original game because the player must kill the boss in one cycle. Definitve Edition fight structure is different which player could only kill in 3 cycles.
Changes to the original game
Original game one cycle demo
Definitve Edition first 2 cycle demo