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For five turns, damage from special attacks is reduced to 1/2. In 2v2, it is reduced to 2/3, and the effect is extended to both Pokémon. The effect remains even if the user switches out. A critical hit ignores the protection. If the user is holding the item Light Clay, the move lasts for 8 turns instead. If the user or its partner is hit by the move Brick Break, Light Screen immediately ends.
Reflect is an equivalent move, but reduces physical attack damage instead of special.