XC2: Cloud King's Revenge in
Almost this entire build was taken from Enel's video, which you can see here: • Xenoblade Chronicles 2: Cloud King's Reven... . I plan to edit and modify this build in the future to try to get an even faster time.
This strategy revolves around abusing an orb master common blade and Elma and kos-mos. I can set up a two orb fusion chain attack very fast.
This build is very very luck based. First, nia must land a break on Ken with a bitball, which only hits once (this is the only reason nia is used at all). Rex also needs to quickly switch over to the orb master common blade (usually he switches first to patroka then the common blade, as he does here). If the break lands, crossette must use her level 1 special with the orb master common out (and this must be timed properly if you want to save time). I wasted several seconds by waiting too long for rex to switch to the common blade. Once you have two orbs set up, you go into the chain attack. Patroka is used so Fiora can hit for elemental weakness, which will add nearly 6 million damage. However, chain attack damage still revolves greatly around Elma and Kos-mos, who hit 16 times each each time they are used. However, if ken blocks too many hits of hundred shells (or fiora/patroka's specials too), you will come just shy of killing him (i had a 52 second run interrupted since he blocked one hit of patroka's level 1 special and 3 hits of hundred shells). Elma and kos-mos's level 3 specials, however, have guard annul so he cannot block it, thankfully. Basically, every hit of the chain attack counts.
Overall, i spent about 4 hours grinding for this common blade and another 2 hours just to get this time. It could've been slightly faster but i sacrificed some time in order to be safer. i'll try to get this slightly faster but i am very happy with this time for now.
gear shown at the end. more challenge mode content soon