Thank you for the cookie and for playing!! I didn't really eat so many cookies, but I had equally unhealthy sleep habits during the jam :D
The Z-attack is a ranged attack, it can traverse roughly half way across the screen.
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that's correct actually, it's an "instant" attack like in Risk of Rain! So there's nothing that spawns and moves, just a raycast that shoots across the screen, then the sparks just spawn exactly where it was hit. You may want to play it full screen to see it. I'm not sure how many other games do it like that, so maybe people aren't too familiar with the mechanic.