Part 13

The fight begins with Warboss Grimskull. If you have the Thunder Hammer, use the Plasma Pistol and Bolter. Otherwise, use the Plasma Rifle and another heavy weapon. Always roll away from his grenades.

Phase 1: The Warboss charges alone. Move backward and to the side, rolling away as he charges. Maintain distance and continuously shoot him with the Bolter (infinite ammo is available from crates). Avoid melee combat on high difficulty. He will throw flashbang grenades, which cause no harm.

Phase 2: The Warboss breaks a wall, releasing hordes of Orks and firing a laser. Roll under the laser or stand in the opposite corner. The Orks are meant to hinder your movement. Kill Orks when they are near, ideally when your shield is nearly full. Use the Vengeance Launcher if available. Evade the Warboss and Orks until your shields regenerate, then focus on the boss. Orks will continue to appear when the Warboss roars.

After another flashbang, the Warboss breaks another wall. Repeat the strategy from Phase 2.

Phase 3: The Warboss is on top of a wall. Move to the opposite wall and throw all your grenades at him, picking up more from crates. Aim above him so grenades land on the wall. Watch out for Squibs he sends down; shoot them near him to damage him. After defeating him, melee him a couple of times to finish him.

Climb the lift to the left and stock up on ammo. Mount the train to proceed.

Enter the door opposite and proceed through the next door into a room with guns and ammo.

After the next door, shoot the guards with plasma shooters from near the entrance.

Move forward, and in the first room on the left, find a Servo Skull.

Proceed to an area with possessed enemies. Shoot them or melee them. Pick up the Heavy Bolter on the first ramp.

Go back and down the other way to find a Daemon Summoner. Shoot the summoner first, then the four guards he summons.

Go through the next door to face four snipers with laser scopes. Use crates for cover and take them down.

Reach the other end of the area and enter the door to activate a lift.

Upon exiting the lift, a Servo Skull is to the left.

Continue to the control room and use the panel to power the Titan.

Go to the room on the right and up the stairs. Kill the two Chaos guards, but do not shoot the explosive canister near them.

More enemies, including a Plasma user, will emerge from a portal. Shoot the canister to eliminate them. Stay at a distance and kill them.

A wave of Chaos demons will appear; defeat them.