Fairy Law (妖精の法律, フェアリーロウ, Fearī Rō) is one of the "Three Great Fairy Magics" distinct to the Fairy Tail Guild, and an improved version of Law.[1][2]
Description
When activated, a bright light envelops the area and inflicts massive damage on whoever the caster perceives from their heart as an enemy, leaving friends and bystanders completely unharmed.[3] The choice between friend or foe is decided by the user's heart, and they cannot lie to this Magic.[4] It is considered one of the most powerful Magics and is one of the rare legendary spells,[5] and also one of the three great Fairy Magics.[1]
The Magic's strength was so great that it defeated Jose Porla, a Wizard Saint, in a single blow, during a battle in the Phantom Lord vs Fairy Tail guild war.[3] According to the second master of Fairy Tail, Precht, Fairy Law is a deterrent Magic, meant to discourage further action from enemies, and is not something that should be used lightly.[6]
Setting Law as its basis, Mavis modified and improved it so that users wouldn't suffer from its side effect.[2]