SRD:Icy Blast (Epic Weapon Enhancement)
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On command, an icy blast weapon is sheathed in icy cold (though this deals no damage to the wielder). On any hit, this cold washes over the creature struck, dealing +3d6 points of bonus cold damage. On a successful critical hit it instead deals +6d6 points of cold damage (or +9d6 if the critical multiplier is x3, or +12d6 if the critical multiplier is x4). Bows, crossbows, and slings with this special ability bestow the bonus cold damage upon their ammunition.