Achievement #3187 (possibly named "Tous Les Arbres Qui Cachent La Freya 25 Joueurs") doesn't exist. It may have been removed from the game.
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Knock, Knock, Knock on Wood (25 player) - Live
Knock, Knock, Knock on Wood (25 player) - PTR
Knock, Knock, Knock on Wood (25 player) - PTR 2
Knock, Knock, Knock on Wood (25 player) - Beta
Knock, Knock, Knock on Wood (25 player) - Wrath of the Lich King
Knock, Knock, Knock on Wood (25 player) - Cataclysm