I haven’t been able to get it myself, but I do know one of the early access streamers was able to do it (maybe if you search his past broadcasts you can find it, his twitch username is MadcowQQ). I’m guessing you’d need to maximize your shield strength and take The Conduit. I’m pretty sure overshield will add to the skill damage as well, so you could theoretically get ~120 extra damage per blade (i.e. you need a Reyna on your team).
Next, I’d either try to either use it on a boss in multiplayer with a lot of minions around (perhaps void’s edge first boss?) or get lucky enough to get all five enemy battleborn together in comp multiplayer. With that amount of damage per blade, you’ll need to pierce at least four enemies with every blade.
Although if it does indeed have a damage cap of 100, you’ll need to pierce at least six enemies (each needs to have at least 400 health as the excess damage won’t count) with every blade which doesn’t seem impossible given the right circumstances.