Here's a retro-style (but accurate to this version) map of the dungeon:
Thanks to Kincaid for making this!
When the fight with Spike Roller starts, begin charging a spin slash and jump over his spike. Hit him with two spin slashes before he gets to the other side of the room, then start slashing him through the spikes.
Moldorm can be killed very easily with two spin attacks. Some runners like to time the second spin slash to know exactly when Moldorm will open up its tail again, either with a music audio cue or by jumping 8 times.