Gonna be jotting a bunch of level ideas down here.
Heavenly Hell: A traditional cave level with many lava fountains and hidden mini-skulls. Helmets include Cyclone and Skycutter.
Morbid Hole: Definitely some sort of Cave level. Helmets include Maniaxe and/or Red Stealth
Familiar Oak: a late game level that mimics Blue Lake Woods 1, except with alot more challenging enemies. Helmets would be the same as Blue Lake Woods 1, so Iron Knight. Might possibly replace the extra life block with a coin and put drill blocks around it.