The ice boot powerup can also defend you from lava droplets (which are a bit harder to dodge) and the Lava Monster (that sometimes occurs later in the run).
Also, thanks for the suggestions! I have just updated the game such that stepping on the devils from above kills them in one shot. I'm also planning to perhaps add a health bar to the player so that the player can withstand multiple hits (i.e. from lava, devil tridents, fire, etc.) before dying. A health boost powerup that appears occasionally would be swell too.