Once the trian has been called and you're waiting to extract, I think a difficultly ramp up would be a good chance to test your build and grind extra souls - similar to Megabonk where it gets progressively harder after the timer runs out. This could add some exciting end of run moments or a chance to fight huge swarms.
#Post Train ramp up
outer berry
pale widget
what if we see a WAVE of enemies approaching toward you?
outer berry
Run onto the train asap I suppose 😂
pale widget
Run onto the train asap I suppose 😂
also a earthquake effect would be nice