The Subterranean Hydra Emperor is a boss in Serious Sam: Next Encounter.
- The Subterranean Hydra Emperor is a beast that lurks under the Ancient Palace. Someone has modified the Hydra's heads with modern technology, such as adding a lasergun and a rocket launcher.
- Each of the Hydra's heads use different attacks. The blue head fires laser projectiles from its cannons and sweeps the area with a laser from its head, the skull head fires drill-like rockets, and the red head sprays fire everywhere.
- After attacking the player for a bit, the heads will retreat and reappear in different areas.
- The heads will appear in this order; skull, blue, red then all three at once for the rest of the fight.
- The red head should be the first one targeted when all of the heads appear. It's fire breath is significantly more damaging than the other attacks and the flame is more difficult to dodge.
- The blue and skull head's projectiles can be dodged by strafing left or right.
- The blue head will occasionally open up and fire a laser that sweeps the ground. When he first starts this, jump. It will allow the player to dodge the laser.
- The XM4000 Minigun and RAPTOR Sniper Rifle work best against all of the heads, as their bullets will instantly hit the heads. It takes too long for XPML4000 Rocket Launcher's rockets to travel to the heads, even though it is quite powerful.
- Remember to stay near the middle of the arena. There are holes all around the edges of the arena, and they lead to a lava pit that has no escape route.