Ring of Pain

An alternative way to unlock the Masochist Achievement is to wear the "Maniacal" helmet gold item before to fight the Final Boss.

Be sure to take enough damage to decrease your defense to 0 before to defeat the Boss.

You need to know the game to understand the strategy shown here, there cannot be a step by step guide given the nature of the game:

When playing on normal difficulty, you need 21 speed points to always attack first.
At that point the defense is useless, it can be replaced by HP and good items.

You can use the Polearm strategy, or you can use as many Splash Damage items as you find