I managed to get to the 5th boss (Reaper) and I just don't understand how to beat him. And the Spider chase was a bit frustrating: too long and to checkpoints.

how do you get past the barrels they only move so far and cannot make the jump

i gave up on this at the snow section boss , just too hard and annoying . up till then it was hard but fair but needs checkpoints moving or adding so you dont have to repeat some of the tricky platforming/dodging sections ... a shame its not balanced well as i enjoyed it up until then...