This was hilarious and somewhat broken. But it's sort of like a reverse roll cancel in CVS2 in that instead of canceling a roll into a special you cancel nova into a roll. The thing is Nova has invincibility on it (thats why you don't get shot out of nova) and if you cancel between the time you start it and the height of your jump, you retained invincibility on your roll. You have to cancel before the explosion, or else you just get a normal nova and use up your barrier. But like in fighting games, theres a really short window after the roll that you can be hit until you start another nova, but it's pretty small and I managed to completely have a grenade explosion on gold pass through me (though it still pushes your jump a little further). I even tested this against a turret and I maanged to roll cancel to it, while taking a few hits, but otherwise I killed it.
This is useful for timer scamming, like at teh extraction point, or wasting time so your charge can come off cd to restore shield. Funny enough, I restored my shields by just doing this because I was dodging bullets in a whole room of people on gold.
BIG WARNING THOUGH, LIKE IN FIGHTING GAMES, YOU CAN BE GRABBED OUT OF ROLLS. AN ATLAS CRUSHED MY FACE INTO PASTE THIS WAY. Though Phantoms never grabbed me out of it, but I just let the nova out anyways to stagger them.
Ok I made a quick video, where I just spammed the technique. It's not hard to do but I screwed up sometimes and went into cover messes with me (having space bar for 5 different things sort of stinks).