Note: the above video guide does a slightly outdated setup for the octo clip. The overall information is still correct but should be applied to the new setup in the demo video to the right.
REPRODUCTIONS STEPS
After the Lantern has been collected and the big door is open, octo clip can be performed to enter the boss without activating the two switches to melt the boss.
Dash down into the room (dash immediately to ensure RNG is correct for the manipulation)
Slide around to the left and activate the top 2 flying pots (or all 3)
Head to the top of the room and break the middle pot
Push the right pot into the middle of the room below the entrance
Walk above the pot and push it down until you hit the Ezlo trigger
Push the pot to the left until it is off the ice (if you haven't already, the 3rd pot will smash with zero chance of it hitting you)
Push the pot down until it is 1 tile from the bottom wall, just like in the image on the right
Note: Each time the clip fails you must return the pot to this position before attempting the setup again
The following is a Subpixel setup, extra care must be made to the following inputs to ensure the correct position is achieved for the clip to work.
Move to the right and slide down against the top of the octo leg before pushing the pot to the left
Important! Watch link's shadow against the octo foot to check your vertical height (as seen in the image on the right), if the shadow overlaps the foot at all then you are too low and should restart the setup.
While the pot is moving, hold Down and do not let go until you are touching the bottom wall
Hold right to make link walk into the side of the octo foot and do not let go until link performs the push animation.
Important! You must have the push animation happen, this will set all of links sliding momentum to 0, having any sliding momentum when not against a wall will change the position enough to make the setup fail.
Tap the gust jar to blast link to the left
Tap down for as few frames as possible to make link face down
Tap the gust jar
Important! Do not use the gust jar instantly but allow a few frames to pass first, you must have 0 sliding momentum or the setup will fail, you build up sliding momentum all the time you press a direction input even if you are against a wall and not moving.
Pause and equip the Sword over the Boots
Slash the sword, then while the sword is in the middle of the animation press up and then press sword again to slash turn facing up
This puts you in the perfect position to perform the clip
There are two options for how to perform the clip, both are frame perfect with the first one being the fastest and the 2nd one giving you some time to feel out the timing.
During the slash to face upwards, hold Up+Left and then time a roll input exactly 19 frames after you slashed (4 frames after link begins to walk)
Tap R to perform a grab, during the animation hold Up+Left and then time a roll input exactly 20 frames after you pressed R (also 4 frames after link begins to walk)
If both your timing and your setup were correct then you will roll diagonally down right into the corner and clip through the corner and can freely enter the octo fight. To continue the RNG manipulation perform 2 rolls down into the boss fight.
If you do not clip, move the pot once to the right and perform the subpixel setup again to re-attempt the clip.
Wall Collision view to show the exposed corner we clip through
Make sure to double check each of the "Important!" notes in the subpixel setup, these are the most likely causes for the subpixel setup to fail.
If you roll upwards: It is most likely you did not roll on the correct frame, there is not much you can tell about your subpixel setup.
If you roll directly to the right: Your timing was perfect but your position setup was incorrect.
If you diagonal roll but do not clip: You are rolling far too late.
If you are facing Left during the roll: You begin holding diagonal Up+Left during the Grab/Slash animation too late.