Null consumes a triangle of Prime Energy, but it hungers for more, so it attacks you and Link.

How to Defeat Null

Null will sometimes shoot claw-shaped shadows at you. Run away from it to dodge it. Use echoes to attack Null's arms. When an arm is destroyed, it may drop a heart.

You can bind to and pull on an arm to help Link hit it more easily.

After the three arms are destroyed, use your echoes to hit Null repeatedly. Its body will break slightly.

Second Phase

Null's arms will come out of the wall. They will shoot claw-shaped shadows. Dodge them and use echoes, such as Goo Specters, to hit the arms repeatedly. As before, the arms drop hearts when destroyed.

Afterward, Null will come back out of the wall and float around, creating claw-shaped shadows with its arms as before. Attack it as before until its body breaks more.

Third Phase

Null will go into the wall and its arms will come out as before. This time, the arms sometimes create a puddle of darkness beneath them, so floor-based echoes won't be able to attack them. Moa echoes are effective in fighting Null during this phase.

After the wall arms are destroyed, Null will come back out of the wall. It creates claw-shaped shadows, and creates puddles of darkness under some of its hands. Sometimes it will use its whole body to dash toward you or your echoes or Link. Eventually, Null's body breaks even more. There will be a cutscene.

Fourth Phase

You now have to swim toward Null and create swimming and/or flying echoes to attack Null. Null will create echoes of bosses you have fought before, which will do attacks from their battles. The Vocavor echo will send water tornadoes toward you, so be sure to dodge them, and send out new echoes if the tornadoes destroy them. Look for large bubbles to swim onto to refill your dive meter.

Fifth Phase

You and Link will battle a larger Null with more arms. Remember to bind to the arms and pull on them to help Link hit them. Null will sometimes turn into echoes of past enemies. The Seismic Talus echo will spin its arms rapidly, so get far away to avoid getting hit. There will be multiple Mogryph echoes, which send tornadoes to hit you or your echoes or Link, so stay out of their path.

Eventually, Null's body will break and you will see the glowing triangle inside.

Sixth Phase

Null's arms will come out of the wall. Null will create echoes of Darknuts to attack you and your echoes and Link. There will also sometimes be a dark glowing spot on the floor. Run away from this, because it will turn into a hand that tries to catch you and trap you. If you're trapped, make sure you have active echoes to attack the hand, and wait for the hand to be destroyed so you can move again. You can bind to the arms in the wall to help Link hit them, but beware of the Darknuts and glowing spots on the floor.

Eventually, Null emerges from the wall. Attack its arms as before.

This time, it creates three echoes of Ganon, which will dash toward you to hit you with the trident.

It will also sometimes create two echoes of Skorchill, which will spin around and freeze you and Link if they hit you.

Seventh Phase

Null will go back into the wall. As before, destroy its arms, but watch out for the Fire Lizalfos echoes and Boarblin echoes, and run away from the dark glowing spot on the floor. Buzz Blobs work well to stop the Lizalfos. Try binding to the Lizalfos and moving them onto the Buzz Blobs.

Eighth Phase

Null's body will reform, and it will sometimes send six Ganon echoes, so be careful to watch which Ganon is about to dash, and get out of hte way. It will also sometimes create a Gohma echo, which will spit spiderwebs onto the floor, so use a fire monster echo to burn those away.

Finally, Null falls onto the floor and stops attacking, and the golden triangle is visible. Bind to the triangle and pull on it. Then when you see the A button on the screen, press it repeatedly until there is a cutscene. Congratulations! You won! Enjoy the ending! Afterward, your save file will have a star on it. Load the save file, and you will now be able to see the total number of echoes, Pieces of Heart, and other things, in your Notebook and the map if you press Y, and you can talk to the Deku Tree to find out which regions you should visit to learn any echoes you're missing. Missing echoes will appear as empty spaces in your Notebook.