Then take six hours, do a couple bonus’ and still 4 star?
Then take the epic power and instead choose another bonus to 4 star; pauper or no duplicate perhaps? (stat /hp oblerons don’t count)
Do three runs at 4 star to unlock layer 12 or run lower layers every week, get 3 stars and still get the full ash amount.
If your gear is still <230 I wouldn’t advise upgrading your legendary past rank 4. It’s just some extra mainstat and secondaries. The special effect won’t change.