Aspic

While in battle, you can use controller 2 to partially control the enemies and gain an advantage.

If you get lost in a dungeon and want to go back to the start, just save the game, change disks and select Continue on the title screen. You'll start the game outside the dungeon.

At the Start/Continue screen, press and hold A, B, Select & Start on controller 1 and start shouting on the Famicom's controller 2 microphone. Keep holding and shouting while the game loads, instead of starting the game, you'll be taken to the ending.