I let my luck dictate how deep I went on Acheron. If I lost my 50/50, then I just wouldn't bother at all and keep saving. If I won, then I would at least try for E1. If I won that 50/50 too, then I'd go all the way for E2S1.
It decided to give me two Acherons and
then
pull the rug and give me a Himeko and Bronya's LC, so I had to dig into
all of
the new top up bonuses, but to E2S1 I got.