Quick Answer
Destroy the worm's final tail segments, then shoot the spider's central cockpit while keeping your distance. You fight both forms in Fortress, with a drop through the throne-room floor between phases. Your main rewards wait beyond the fight on four short plinths.
Where do you find The Emperor?
You find The Emperor inside the palace in Fortress, where he first appears as a mechanical worm.
Before entering, check your weapon build for the two different targets ahead. Once you reach him, expect two connected fights rather than a single health bar. Defeating the worm opens the route to his second form; it does not finish the encounter.
The first arena gives you a segmented target moving through walls and the floor. The second puts you in a narrow, circular tunnel with a mechanical spider or crab pursuing you. Your target changes between forms, so aiming at the same body part throughout will not work.
How do you beat the mechanical worm phase?
Shoot the final tail segment until it detaches, then repeat as The Emperor becomes shorter and faster.
Choose a weapon for brief openings
Use a weapon with high damage per shot because the tail stays visible only briefly. Shotguns, rifles, and sniper rifles can work. Your ability to track and lead the moving tail matters alongside weapon choice.
If you need help choosing, compare the best weapons before returning. Here, the useful quality is damage delivered during a short opening.
Follow the last segment
Only the final segment can take damage during this phase. Keep shooting that sphere until it separates, then find the new end of the tail.
Each lost segment makes the worm smaller and faster. Keep tracking the remaining tail as the target shrinks. You eventually reduce the vehicle to its cockpit and one tail segment.
Avoid shockwaves and sulfur
The Emperor lunges toward you and travels through the arena's walls and ground. Diving underground creates area shockwaves; emerging can produce them too. Reposition and jump to avoid the waves while watching for the tail's next appearance.
Detached segments leave sulfur on the floor. Walking through it reduces your visibility and movement speed. Avoid crossing those deposits while trying to follow the increasingly fast worm.
Prepare before dropping into the pit
After you empty the worm's health bar, a hole opens in the throne room. Heal and check your weapons before jumping through it. If you need food options before your attempt, consult the best food guide. You meet The Emperor again below, and brief dialogue leads into the second phase.
How do you beat the mechanical spider phase?
Keep moving around the circular tunnel and shoot the middle section, where The Emperor's cockpit sits.
Keep the tunnel clear behind you
The Emperor constantly advances, so move backward around the arena while firing when you can. Watch walls and obstacles: getting caught gives him a chance to close the gap.
Use the tunnel's curve for protection because the passage offers little other cover. Let distance decide when you shoot. A few extra hits become dangerous if they let the spider reach you.
Handle rockets and reinforcements
The Emperor fires slow rockets with predictable paths. Keep moving to dodge them; shooting rockets can also disrupt their trajectory.
Additional Shav'Wani enemies spawn during the encounter. Use grenades to stop reinforcements from overwhelming you, then return your fire to the cockpit. Keep checking your route while dealing with these enemies, since the boss continues advancing.
Take openings without losing distance
Choose moments to attack while preserving room to move. Aim at the central cockpit whenever you have an opening. If firing lets The Emperor get too close, prioritize movement and create space before attacking again.
Do not carry the worm strategy into phase two. You need the spider's central cockpit, and maintaining distance matters more than landing extra shots.
What does The Emperor drop, and where do you go next?
The Emperor himself has no notable drops, but four short plinths beyond the arena hold valuable loot.
Possible rewards include Weapons, Insurance, and Chamber Chisels. Treat these as possible finds; you are not guaranteed every listed reward each time.
When The Emperor dies, the remaining enemies disappear too. Collect your rewards, follow the newly opened route, and jump from the cliff at its end to enter the Desert.
Use the SULFUR bosses guide to check other encounters after clearing Fortress.
FAQ
Yes. His Most Holy Emperor is The Emperor, the boss you encounter inside the Fortress palace.
Only the final tail segment can take damage. Shoot that segment until it detaches, then target the new last segment.
No. Jump into the newly opened pit, where dialogue leads into the mechanical spider phase.
Shoot the middle section of the mechanical spider, where its cockpit is located. Keep moving so it cannot close the distance.
No. The four plinths can contain Weapons, Insurance, and Chamber Chisels, but you may not find every reward.