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Arrow of Ill Omen
Bard Attack 5

The arrow you fire is a harbinger of your foe's doom. Where it strikes, death follows.

Ranged weapon

Target: One creature

Attack: Charisma vs. AC

Hit: 2[W] + Charisma modifier damage.

Miss: Half damage.

Effect: Choose an ally within 10 squares of you. Until the end of the encounter, when that ally hits the target but does not score a critical hit, you roll a d20. If you roll a 15 or higher, that attack becomes a critical hit, and this effect ends.

Arrow of Ill Omen is a daily power available to bards at 5th level.[AP:9]