“The source of the Taken energy appears to be at the top of the Citadel. Ascend the spire.”
Go forward into the Juncture. Above the first room you will find a Taken Hobgoblin waiting to snipe you. Toward the stairs you will find more Taken Vex: a Taken Minotaur and some Taken Goblin. Head up the stairs and toward the lift upward.
At the top of the stairs you have another Taken Hobgoblin waiting for you. Beyond the corner there are more Taken Minotaurs and Taken Goblin. Another Taken Hobgoblin lingers to the right of the next set of stairs.
Clear them out and more Taken will appear. Defeat them and make your way over to the lift to the top of the elevator and get to the Terminus.
Now you need to make your way across the time-fluxed platforms. Pay attention to the timing and work your way steadily across. The platforms work differently
When you make it to the center platform, a number of Taken Phalanx will appear. Be very careful because they are trying to launch you off this small platform. When you see their shields come up, get behind some cover to avoid the burst of energy coming from them. From there just complete transversing the massive gap.
On the far side you can see the massive bundles of Taken energy. be ready for a fight the moment you touch down on the far side.