The Returnal Ixion boss fight takes place at the summit of the mountain in the Crimson Wastes and while Phrike, the first boss, wasn't too difficult to see off, Ixion is a different beast entirely. The Returnal second boss is almost entirely airborne, making it a difficult fight, especially since during some phases you simply can't damage it whatsoever. So if you're struggling, keep reading for a Returnal Ixion guide.
How to beat the Returnal Ixion boss fight
Let me preface this by saying that the only gun you should be taking into the Returnal Ixion boss fight is the Tachyomatic Carbine. The Spitmaw Blaster doesn't work because Ixion always keeps its distance from you except in the final phase, the Modified Sidearm can do the job but will take ages, and the Hollowseeker is just one of the worst guns in the game.
With that in mind, and the Tachyomatic Carbine equipped, the Ixion boss fight begins when you hop into the arena. As with all the Returnal bosses, there are three phases, and the first phase is the easiest; never let Ixion out of your sight and keep your finger over the dash button. It will dash from one side of the arena to the other, firing a lot of general shots in a wide pattern, but one attack will also follow your movements. Dodge constantly when this is chasing you, then fire your Carbine whenever there's a lull in the shots coming at you.
The second phase kicks off without any targeted shots, but a lot of equally-spaced big blue balls to dodge, along with a tall forcefield wall to jump over repeatedly. Rather than pressing circle to dash here, weave your way through the shots by strafing and jumping over the walls, while hip firing your Carbine.
After a short while, when Ixion leaps off the ground again, flee to one side of the arena. You want to be perpendicular when Ixion zooms back across and unleashes more shots and walls – oppposite the ledge you entered the arena from is the best spot. Dodge all of these attacks and Ixion will return to doing what he did in the first phase by staying stationary with similar shots. The only thing to watch out for is when he goes to the side of the arena with the big spire, make sure you strafe because he's about to fire a huge beam.
Then there's the third phase. It begins in a very similar manner to the second, although when jumping the walls, watch out for the shots above your head so you don't jump into more damage. After this, Ixion will start dashing towards you and slashing, so the importance of dashing away here cannot be understated. Keep backing off. dodge the constant outward pulses when he bangs the ground, and Ixion won't survive for long.