[sblock=Chains]Hmm, I had forgotten about that. The wording of the power is "If the target moves before the end of your next turn, it takes 2d6 extra cold damage," Compare it to the wording of a Swordmage's Chilling Blow, "target takes cold damage equal to your Constitution modifier each time it attacks until the start of your next turn."
I'm inclined to say that the damage can only happen once, since the condition is if the target moves, not each time the target moves. It's a little brutal for a level 1 encounter otherwise.
Judge? Have any words of wisdom to impart upon us? I admit that I'm a little uncomfortable using precision of language as a basis for interpreting powers, given WotC's wretched track record with saying what they mean.[/sblock]