Hey np!!
For the transition from the battles to the platformer gameplay what you could do is skip any kind of fade to black transition and instead start with a fade in from white (actually a light grey usually) so it's even faster than waiting for fade out -> waiting for fade back in. I also like it being really quick so this transition (I imagine being like 0.15 sec long), could make it feel polished while keeping it quick too.
Ahh that's what I was supposed to do with the spikes okay! I think I totally just missed the sign, maybe you could add a shimmer effect + something that makes it grab your attention FX-wise when it first appears will do the trick.
Excited to see what's next!!