Minecraft wiki entry for Enchanting_mechanics, associated text: The power of each enchantment type is determined by the level and the values in the enchantments levels table. For each power value of an enchantment type, there is a minimum and maximum modified level that can produce the enchantment at that power. If the modified enchantment level (calculated at the first step) is within the range of an enchantment's possible power values, then the enchantment is assigned the modified enchantment level as power. If the modified level is within two overlapping ranges for the same enchantment type, the higher power value is used.