This page of the guide to Marvel's Guardians of the Galaxy contains a detailed description of the boss battle against Grand Unifier Raker - this is the largest battle in the game and happens in Chapter 15 (Broken Promises). We advise on how to handle the opposing Unifiers, how to progress to the boss fight proper, how to respond to Raker's attacks and how to weaken the Grand Unifier.
Phase 1 - Defeating a group of Unifiers
Grand Unifier Raker can be considered the final boss of the game. The actual final boss faced in the final chapter doesn't even have a health bar and is a much simpler fight in general.
You'll encounter Raker many times throughout the game, but the actual battle against him happens after the scene with Nikki at the beginning of mission 15. Interestingly, your previous decisions may have weakened Raker by depriving him of a limb. If you let Gamora pursue Raker in Chapter 8, this means she was able to cut off his arm. This decision affects the battle's difficulty - Raker is a bit easier to deal with if his arm got severed.
You can't start fighting the Grand Unifier right away. First, you must deal with four regular Unifiers.
The enemies are weak to lightning, therefore you should be using lightning attacks during the battle. Make sure to only attack the opponents that aren't protected by Raker's energy barrier. Otherwise you'll be wasting time destroying the barriers.
After you manage to fill a Unifier's stagger bar attack him with the entire team's strongest skills. Once you bring a Unifier down to the verge of death, there's a chance you'll be able to trigger a stylish attack by pressing two buttons at the same time. Do it whenever you can, you'll dispatch the enemies quicker without prolonging the battle.
Always keep moving and don't let the Unifiers get too close in fear of their dangerous melee attacks. Their other attacks are equally as dangerous:
- Bombardment (example shown on picture 1) - move away from the red circles on the ground, which signal where the explosions will happen.
- Moving energy walls (example shown on picture 2) - try to go for a perfect dodge or fit in the gap between the energy streams to avoid getting hurt.
During the battle Star-Lord can be trapped in a forcefield as shown on the picture above. This, however, doesn't mean you'll have to stay in one place. A double jump will get you out of the trap.
Phase 2 - Defeating the main boss
By defeating the Unifiers you'll progress to the second stage of the battle. This time you're facing the Grand Unifier Raker himself.
Additional note - The game creates a checkpoint between the two phases. You won't need to fight the Unifiers again if you die to Raker.
Raker's basic attacks are identical to the regular Unifiers, which means he can use bombardments, energy walls and forcefield traps. We've already described how to avoid these attacks.
Raker can also charge, which is signalled by a red exclamation mark. To avoid his charges you must dodge sideways at the right moment, otherwise he'll knock you down to the ground and deal a lot of damage.
Raker is surrounded by a yellow barrier which unfortunately doesn't have any weaknesses - you can't use any elements to break it down faster.
Keep shooting him with your blasters while using the Charged Shot perk to increase your firepower and cool down your guns quicker. This should significantly shorten the fight.
Your objective during this battle is emptying the barrier bar and temporarily shutting it down. Use this opportunity and unleash your most powerful attacks to deal as much damage as possible before the barrier appears again. One of our recommendations is the Fan the Hammer skill which lets Star-Lord rapid-fire his blasters. Make sure the other Guardians use their most offensive skills as well.
One of the more annoying things about facing Raker is that the arena gets periodically shrouded by darkness. Unfortunately you can't interrupt this in any way. Each time the darkness falls, you have to wait it out.
As you wait for the darkness to disperse, you must keep moving and watch out for red exclamation marks which keep warning you about the boss' attacks. You should especially watch out for his charges and the bombs landing on the ground.
It's almost certain that you'll need to revive your teammates during the battle. Help your allies as often as you can, but only when Raker isn't charging any new attacks at the moment. Try to "revive" your teammates when their health drops to zero or if they're weakened somehow (for example, by getting frozen).
Raker has several health bars, so be ready for a long battle. Defeating the boss rewards you with the Faithless achievement.