After important events unfold in Ferenia, you can explore a new part of Burenia.
Get an Energy Part
Go to the left and go through the door there. In the next room, go downward, then slide through the tunnel at the bottom, and Speed Boost past the fan to get the Energy Part. Jump while still Speed Boosting (or just start another Speed Boost) and you will speed boost through the wall on the left. Afterward, go through the door on the left.
Go Through the Gate
Speed boost to the left (or just go normally), then at the end, if you are speed boosting, you can wall jump off of the left wall, ready a Shinespark on the ledge, then enter the tunnel and press B and tilt rightward on the left control stick to Shinespark through the tunnel. Or you can just go through the tunnel normally. At the end, you will see the gate above you that was raised during the previous cutscene.
Go up the left side and go through the door at the top. You will reach the map room. Stand on the glowing panel to get the map of Burenia and save the game. Then go through the door on the left.
Use the Grapple Beam to destroy the Grapple Beam block on the left. This will give you a shortcut to the area below. You can optionally use the Ammo Recharge Station. Then make your way up the room. At the top, grab the blue wall and climb as far up it as you can. Shoot a missile to the left, then do two Flash Shifts in quick succession to the left to grab the ledge and roll through the tunnel on the left. You will drop through a Pitfall Block on the leftmost side of the tunnel, and you can get the Missile+ Tank from there. Go to the right to fall through another Pitfall Block.
Then go to the Grapple Beam door on the right and pull on it with the Grapple Beam until it opens. Go through.
Go to the right, use the Grapple Beam on the creature on the ceiling when it is glowing blue, to pull its outer shell off, then do a Melee Counter when it flashes. Then go to the right side of the room and slide through the tunnel. In the next room, use the Grapple Beam on this ceiling creature as well, then go to the right and open the Grapple Beam Door.
Go downward, to the bottom left of the room, where there is a Grapple Beam Block. Pull on it with the Grapple Beam to destroy it, then roll through the tunnel. Use Flash Shift to reach the upper left ledge, then shoot the bottom block of the wall with a missile to reveal a Missile Tank. Take it, then go back through the tunnel on the right to return to the previous room.
Go to the right side of the room, then make your way up. There is an Energy Recharge Station at the top. Below the Energy Recharge Station, if you go to the left, use the Grapple Beam on the ceiling creature when it is glowing blue, then go left and you reach a tunnel. Roll through it to the next room.
Jump up onto the ledge, kill the creature there, then jump up onto the ledge on the left. Jump up into the tunnel above that, and roll to the right. Get on top of the platform above the tunnel, then use the Grapple Beam to grab the blue wall at the upper left. Do the same with the blue wall above that, then use the Grapple Beam on the swing points in the ceiling to swing to the upper right ledge. Go to the right, kill the door creature, then go through the door.
Pull on the Grapple Beam Block to destroy it, then roll through the tunnel. You will fall through Pitfall Blocks at the end.
Shoot the tentacle at the top of the room. If the creature pulls back its lowest tentacle, jump to avoid when it whips the tentacle toward you, then jump again to avoid the next tentacle. The creature may throw three flame orbs above you, which float downward at you. One is red, and the other two are blue. You can destroy the blue ones with the normal beam, charged shots, or missiles, but the red one can't be destroyed, so destroy one or more blue ones so you can move out of the way of the red one.
Eventually, the device to the left will turn green. Shoot it with a charged shot to turn it red. The water will temporarily drain. Use the Grapple Beam on the blue ceiling and it will take you to the other side of the room. Shoot the device on this side with a charged shot as well. The water will completely drain. Shoot the boss until you can shoot the pink thing. Keep shooting it until it raises its tentacle. Perform a Melee Counter when you see the spark, then shoot repeatedly with missiles or charged shots.
At this point, it may have three tentacles facing you. Use the Grapple Beam on the blue ceiling to avoid them, then drop down when it raises the small tentacle to block your shots. At this point the boss will shoot out two red flames and one blue one.
Repeat these strategies until there is a cutscene and the battle ends.
Go to the Next Area
In the room where you fought Drogyga, go to the middle of the room to fall through Pitfall Blocks. Slide through the tunnel on the left. You will end up on a ledge just above a small blue wall. You can do two or three Flash Shifts to the right to reach the right side of the room (the platform below is made of Pitfall Blocks), or you can swing to the right with the Grapple Beam instead if you prefer. Then slide through the tunnel on the right.
Shoot the red thing in the wall on the right to open a path to the Energy Recharge Station. Then go back through the tunnel to the left side of the room and climb up the nearest blue wall, and shoot the flying creature above you, then use the Grapple Beam on the blue walls to make your way to the top of the room (the ledges here are all made of Pitfall Blocks). At the top, you can go through the door on the right to reach a Save Room. Leave the Save Room and shoot the red thing in the ceiling to open the path to the elevator. Use it and you will go to Ghavoran.