My idea is to only get 2 Mega Rushes instead of 3 in the sewers; overall 3 mega rushes instead of 4. This means that instead of a 25 max damage, I would have 20 I believe. It takes approximately 40-45 seconds to get the third mega rush. Magnus isn't a concern: 5 power bounces instead of 4. Shadow Queen would require 11 jumps, which is the main concern, but that is a 0.4% chance (higher than mega rush drops) so that's fine. But does everything sound right? I can easily not lose 40 seconds because of this
I'll probably just end up getting 2 and playing normally without optimization all the way through to make sure everything works out alright. In addition to all that, I think it would be best to get one mega rush, so damage is 15, go to Chapter 7, beat Magnus, on the way down to the thousand-year door you could go east instead of west and pass by hammer bro fight and get another mega rush there. Otherwise it costs like 20 seconds to reload the hammer bro in the sewers before Chapter 7.