Inaccurate?

Rabid Bear Strike

(Tome of Battle: The Book of Nine Swords, p. 88)

Tiger Claw (Strike)
Level: Swordsage 6 (Two Tiger Claw maneuvers), Warblade 6 (Two Tiger Claw maneuvers),
Components:
Casting Time: 1 standard action
Range: Melee attack
Target: One creature

With a ferocious roar, you leap upon your enemy like a wild beast, slamming your weapon into her with a madman?s fury.

You focus your primal fury into a single attack, laying an opponent low with a mighty blow that splinters bones and shatters steel. As part of this maneuver, you make a single melee attack. You gain a +4 bonus on this attack roll and deal an extra 10d6 points of damage. After completing this maneuver, you take a ?4 penalty to AC until the start of your next turn.