-( Story related, cannot be missed )-
Level: Dark Citadel
The final boss of the game, which had so little to begin with, has you pitted against Sage Gol and his sister, Maia. Corrupted by Dark Eco, they intend to open the Dark Eco silo. You are tasked to stop them, so you're sent to fight a giant Precursor robot.
When arriving on top of the silo, you will find spots of Yellow Eco. Pick one up, switch to your goggles, and then aim at the eye that's shooting a laser. With enough shots, it will disrupt the laser and piss the two baddies off. They will back away and shoot a bomb at you while the Blue Eco vent opens. Run through it and then use the jump pad to clear the blast.
The robot will near the silo and drop some Lurker seeds into the Dark Eco. The beasts will be hazardous, so use the Yellow Eco that will sprout out when one of them does to shoot them away. When you clear all of them away, another bomb will be tossed onto the silo, so repeat as described before.
Now it will attempt to slowly blow you apart by employing some charged explosions from its arm. You can either wait until they discharge, jumping over each ring of energy, or do so while using the Yellow Eco to hit at the arm. Either way, once you've destroyed the shooting mechanism of the arm, it will once again shoot a bomb to pry the Silo and destroy you in the process. Repeat as before to enter the next stage.
Well, it does have two arms. Now it'll use the left arm to shoot cannon blasts at you. Employ the same technique of using Yellow Eco to blast away. With little left but its mine shooter, this will be the last stretch. All four Sages will work together, channeling the Eco energies through the top of the Silo to create White Eco. It will be difficult, but you have to scoop up a single ball of White Eco before all of the mines discharge. The problem there is that the White Eco sporadically spawns throughout the top of the Silo. You have to be quick to get to one, as they will also despawn after a short amount of time. But once you manage to pick up even one, that will be it. Game over for Gol and Maia, and you will have finished the story!