Descent is the 8th level in rapture and one of the easier ones in the world.
Go through the stationary blades as they appear. Hug left for the horizontal ones until you reach the two fast saws. Here jump in a small loop, you should slip right through. On the three vertical saws, stand over the middle one and right before it hits you jump and quickly loop under, navigate the final jump with three blades to win
Getting an A+ is very easy as long as you navigate the final jump quickly.