Deep in Dreamland Floor 45 i-frame + sick dodge by HoT sheesh

00:00 - Secret Technique
I doubt the first 2 is needed, just 80 initial SP will do.

Apparently Floor 45 seem to be the hardest floor. But once you realize the boss has very little HP, you can win by bursting it down before it Ults, or just dodge the attacks.
Floor 50 have the same boss, you can turn off auto play and time your Ults to dodge the nuke too.