The skill converts the user's wrath into energy; the angrier the user is, the greater the power. Additionally, the power of the user grows the longer the user fights. In other words, in a battle of attrition, the opponent will be at a huge disadvantage against the user.
However, the power of the user only grows for as long as the user still has Magicule reserves. If the user runs out of Magicules, it's game over. Moreover, the longer the battle lasts and the stronger the user gets, the more of the user's sanity is chipped away, leading to him/her being nothing but an absurdly powerful creature of rage.