When maxed out and combined with other + Crit% talents and natural Crit% from high-agility rogues, this all but guarantees a critical strike on the biggest Instant-Damage opener Rogues have. Useful for Preparation Rogues, who can vanish twice in a fight, to make for a maximum of three ambushes (Assuming the Rogue is not knocked out of stealth while Vanished and all the Ambushes hit).