Really not clear on what purpose Huraijin serves...

[Baklavah]

It slows down the whole Ninja rotation for no reason, when you should be using Armor Crush in the first place. Plus, Huiton activates from Mudras and stays active using the AC combo.

WHY? Huraijin is a worthless extra button :/

[Stormcaster]

It's for quick recovery if you ever drop Huton. Faster than manually recasting Huton and doesn't waste Mudras.

[Reimmi]

Yeah it's not a rotational ability its a recovery tool

[NelsonVGC]

It is not part of your rotation. Is a GCD to recover in case you made a mistake or downtime makes you unable to reset Huuton. It is more efficient than using a mudra for that, as it only uses one GCD and it has a potency.

[Mithron]

It's very useful in extremely long downtime moments when your Huton falls off in a fight because boss jumps away, you can use this for one GCD and keep two Mudra since you won't be able to Hide reset. It makes re-openers much better. Extremely useful in older synced/minilvl content.

[angienessyo]

I strongly prefer having Huraijin over wasting my mudras to get huton back up. Back in Shadowbringers when every fight had like, a 5 minute cut scene in the middle of it it was obnoxious. E8S was especially awful for this if I wasn't super exact with my final armor crush in adds phase. It's not the greatest button ever since it being a GCD instead of OGCD makes our reopeners after HC1/HC2 a little clunky, but it's way better than throwing away a raiton in your burst because you had to waste a stack of mudras on Huton.

[wereotter]

Also it's good for if you're learning a fight and die, you don't have to use mudras to reapply huton.