Be advised that with the step-up gacha for the "gacha-only" Mum, the usual rates for the premium roll have been altered:

1st Step: 11 premium 3-6* roll for 4500 NG:

3*: 80% (previous: 63.5%)
4*: 14% (previous: 30%)
5*: 5% (previous: 6%)
6*: 1% (previous: 0.5%)

These are worse odds than normal, even with the 6* rate being boosted from 0.5% to 1%: the chance to roll pure salt (3-4 only) goes from the normal 47.7% to 50.6% (the overall rate of rolling one 6* went from 5% to 10.5% though). And you get to pay 4500 NG for this! Woo!