The Big Key Skip requires doing Portal Items with the Mole Mitts at the Minish Portal on the third floor. Place a bomb above the portal and perform Portal Items:
*If you let go of up too soon after you press the Mole Mitts button, you will get a glitched Mole Mitts animation that takes around 10 seconds to end, so be careful.
Once you've performed it, wait until the third bomb flash (the third flash is one frame so it's easy to miss!) and start pausing and unpausing until you are on one of the good frames shown below:
|Third flash (bad frame)||In between frame 1 (good)||In between frame 2 (good)||In between frame 3 (good)||In between frame 4 (good)||Fourth flash (bad frame)|
*If you climb up from the bottom half of the portal, it's very likely your subpixel value is too high which makes the trick fail on all frames.
Once you've paused on the correct frame start holding up and unpause. You should jump off the portal and the bomb will boost you out of bounds. Afterwards, head to the room to the left and jump off of the top door frame to get on the correct layer and proceed to the boss.
If you go in without jumping down the door frame, you're on the wrong layer and won't be able to hit Mazaal. You can head back to the previous room after the cutscene and then jump off. Be careful to not go directly to the boss room after going OoB or you'll softlock the game.
On the European version only, it is very important to pause the game before heading to Mazaal or the game will softlock in a different manner.
It is possible while having one hand stunned to place yourself close enough in the palm to have the other hand not be able to hit you
The pillar with the eye in Mazaal's head is never in the same place two times in a row. Use this to route your digging for the 5 other pillars effectively.