The Loss of Heart prayer is a prayer from the Befallen prayer book, needing 45 Prayer to use. Loss of Heart is an offensive prayer that affects the opponent of the user. When the prayer is activated, the opponent's maximum hit with magic will be decreased depending on the user's health. For every 25% of the user's health that goes below his maximum, the opponents magic max hit will go down by about 20 hit points, ie: The user is on 30hp/40hp, and his opponents magic max hit is 143, it will go down to about 120-123. This curse is more commonly used my lower level players, as there are other more powerful prayers in RuneScape that amount to the same thing.