This Guild Event was really easy to be honest
Squad: Roglizer LS, Amus, Daltisk, Mordred, Shion (later replaced by Elaina) and a Harlequinn friend.
I don’t know why some people are talking about UBB wipe but that definitely didn’t happen to me, I used Roglizer’s UBB on all battles for the Hit Count+ and maybe his 100% Mitigation cancels the Wipe. On last battle I used Elaina’s UBB like 3 times and there was no wipe on any of my units or maybe I was just lucky and evaded.
By the way Double Recast, 1 Extra Action and units with hight hit count definitely helped me speeding up the process, it was really easy plus with Mordred, Harlequinn and Elaina’s UBB I was able to use SBB like 15 consecutive times in 1 turn, no joke, really powerful.