Saix is the third boss on the Limit Cut mode of Kingdom Hearts 3 Re:Mind and the first to introduce a special charge meter to the fight. Saix fights with a collection of double-sided axe-like weapons that he will constantly hurl you at you and create large AOE damage zones. As he takes damage, his Berserk meter will begin to fill, first yellow and then blue. Once it feels all the way blue, Saix will go into a Berserk mode and then you've got a real problem on your hands. Use this guide if you're struggling with Saix: we'll walk you through his attack pattern, how to counter him, and if you're really struggling, how to just completely cheese this fight.
Getting Geared Up
You're not going to be able to slide right into Limit Cut after finishing the story without some grinding. I finished both the base game and Re:Mind around level 45 and was getting absolutely housed by the Limit Cut bosses on Proud Mode. While there are those that manage to pull off level one crit runs with one hand behind their back, the rest of us need to be prepared.
First step is getting the right Keyblade. Assuming you haven't gone through the process of getting the Ultima Weapon, your options are either Oathkeeper on Normal/Proud or Oblivion on Critical. All you need to do to get Oathkeeper is find all 90 of the Lucky Emblems scattered around the worlds. As for Oblivion, simply complete the game on Critical.
Once you've leveled the Oathkeeper up all the way, I recommend using the Royal Ribbon and 2 Cosmic Belt+. These three items will give you the highest defense and resistance combo possible
As for accessories, I like to use the Crystal Regalia from the Dark Inferno secret boss and the Mickey Clasp, again from the 90 Lucky Emblems, for the fastest MP regeneration. The third slot is more open to preference; Orichalcum Ring, Flanniversary Badge, and Celestriad are all good choices.
After that just make sure you have a Kupo Coin, lots of Hi-Potions and Hi-Ethers (or Elixirs if you're boujee) and eat a high HP/defense meal.
Saix's Move Set
Lunge Attack - Saix will lunge at you. It's pretty easy to block, but if you're quick enough on the dodge you can actually get a reversal on him and start an early combo.
Axe Throw - The axe Saix throws will track you and then create an AOE zone when it lands - just dodge this one at the last possible second to avoid damage.
Spin Attack - Saix spins at you three times, alternating the side he attacks from. Block all three and then immediately counter the third one to get a combo in.
Ground Slam - When Saix slams the ground, there will be two waves of purple energy that charges towards you. All you need to do is walk dead center to dodge the first wave and then slight dodge to the right to avoid the second one.
Berserk Mode - Once Saix powers up his Berserk meter all the way, he's going to start doing a lot of attacks that are nearly impossible to avoid.
Berserk Axe Throw - Saix tends to throw a bunch of axes and then charge at you. The best thing to do is avoid the axes and then dodge the charge attack.
Berserk Big Explosion - Saix throws out a bunch of axes that then explode after a short delay. You can jump to avoid them, but you'll open yourself up to a nasty follow up combo. Try to find a spot on the ground where you'll be safe.
Berserk Ground Slam - Saix teleports above you and slams down, making energy waves in all directions. Move away from him quickly and then try to slip in between the waves.
Berserk Dash - Saix will start dashing around making tons of AOE damage circles behind him. You can start flying to avoid this, but he'll probably still hit you with an axe. Expect to take some hits when he does this.
The "Get Good" Strategy
When the fight starts, Saix will float up into the air and burst. Wait for just a moment, and then rush in for an early combo. Watch him closely while you combo him because you'll need to throw a block in here or there before you continue. You should absolutely be using counter kick to close the gap on him because Saix teleports around a lot.
When he floats into the air and says "I call on the moon's pale light," get away from him because he's going Berkserk. You'll get him into Berserk mode fairly quickly and at this point, you should start playing much more cautiously. Dodge all of his axe throws, explosions, and ground slam and never stop moving. The meter drains very slowly, but faster while you damage him. Your best opportunity to get damage in is immediately after a ground slam attack if you managed to avoid it and you're close enough to him. Try to stay close to him while he's berserking.
Hopefully, you've managed to get your Dual-Wielding charged up by now because the finisher attack can actually drain his Berserk gauge quickly. If you survive, Saix will be stunned out while he refills the yellow meter, this is your chance to go ham on him.
Occasionally Saix will quick charge his Berserk meter - fire a Blizzaga at him to stop the charge and then wail on him. When he goes back into Berserk and starts doing the dash attack, just move away from him and unleash some shotlocks for big damage and massive drain to his Berserk meter.
The "Cheese" Strategy
Saix in Berserk mode is pretty hard to counter, so here's something you can use if you just can't survive his combos: As soon as he triggers Berserk (after his initial floating invulnerability thing) trigger Simba and start pouncing. As long as he doesn't start with the dash you can stun-lock him in the corner and drain his Berserk meter. Do this every single time he does Berserk and you'll never have to deal with it!