Momiji can heal thats why so your partner can't ever die unless you get grabbed at low health or ninpoed by genshin
also just beat UN8, was the most luckiest round ever, i was distracting genshin while my partner was killing 2 dokus, i saw doku do the ground slam and i tried to dodge it but it hit me so I had 0 health, if i got hit once i would insta die, friend managed to kill 4 dokus and 2 genshins in 30 seconds LOOL talk about OP sythe lololol
edit: oh yeah just beat un7 right after 8 first try woo! 9 and 10 left!