Polycephalus is probably the most disturbing-looking boss in the game. It appears as a mass of undeveloped fetuses melded together from a giant half buried one (with total four heads). Each heads possess with empty eye-sockets streaming with bloody tears. It also appears to have several arms.
Polycephalus have few types of attack patterns, however before performing any of them it will burrow under the ground and become invulnerable, then burst out of ground and attack.
- Spray out a barrage of blood shots towards the character in a similar fashion as Monstro.
- Fire a spread-shot of 3 shots towards the character.
- Summon a Round Worm.
- Fire 8-directional shots.
Notice that the sound he makes before using each attack is different.
Polycephalus can not pop up right below the character; It usually appears in front of it. By standing still and shooting at it right after it appears will quickly finish the battle.
Polycephalus receives two champion variants for the Afterbirth DLC.
- "Polycephaly" is the condition of having more than one head.
- On Catacombs XL, it is possible to fight Polycephalus in both boss fights.