Part A: Kill the bats and go to the left first.
Part B: Hit the button to open a tunnel above you to get another potion.
Part C: If you hit these balls once, they freeze. So hit them on the side that has nothing on them.
Part D: Hit the buttons here quickly and go to the right first.
Part E: Go left first.
Part F: Go right first.
Part G: Hit a button to go right.
Part H: Don't forget to pick up a potion here.