Ryu Hayabusa
The scrap metal vortex isn't really going to do much offensively (even minions mostly ignore its damage) and I don't have confidence in Mordekaiser to land any hits on Ryu Hayabusa other than his Children of the Grave ultra (which isn't a ohko-- pretty much by definition) and maybe his life siphon. Hayabusa can probably just activate art of the firewheels and flying swallow repeatedly for the win here, though he's capable of much more interesting attack strategies if necessary, like using exploding anti-tank arrows to get Morde at a distance, cause we know Morde can't handle being kited very well!
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No problem!
This is a cute and pop genocide of love!