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Crackling Burst
Swordmage Attack 1

Your weapon sends out sprawling arcs of lightning that hit nearby creatures, making movement agonizing for them.

Target: Each creature in burst

Hit: 1d8 Lightning damage. If the target moves during its next turn, it takes lightning damage equal to your Intelligence modifier.

Crackling burst is an encounter power available to Swordmages at 1st level.[AP:51]

This power is a terrible choice, as the recommendation is to choose Sword burst as an at-will instead of this power. Compared to the other power, Crackling Burst inflicts less damage and doesn't avoid allies. Even if the target moves, it only provides one point of extra damage on average.