It's possible you've seen me in the lobby. I have 4 characters that I use with 2 of them being Dark Falz characters, one is Getthemult (aka Elder) and the other one is Fleur (aka the female Gemini twin). One of my other characters is Selvaria Bles from Valkyria Chronicles. But yeah after 3 fights and some forum reading I learned when not to attack Shiva. I do definitely see people still die though from her counterattack though. I generally get an A rank though because my team usually can't kill the two bosses right before Shiva and Varuna fast enough. I've gotten 2 S ranks so far funnily enough.
Hmm off the top of my head I only recall seeing a Dark Falz Luther regularly! I play at strange hours though.
That’s why I only get A rank, too. My group never kills both bosses in time. Someday I’ll get an S rank.