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Spinning Sweep
Fighter attack 1

You spin beneath your enemy’s guard with a long, powerful cut, and then sweep your leg through his an instant later to knock him head over heels.[PH:78]

Target: One creature

Attack: Strength vs. AC

Hit: 1[W] + Strength modifier damage, and you knock the target prone.

Spinning Sweep is a first-level fighter encounter attack power, and is recommended as part of the Great Weapon Fighter build.