Looks good for a first monster!
The starting size beyond 4 may increase the level by 1 more. Also I see Unencumbered Dodger 4 times and scaling passives are not normally stacked and are usually restricted from being used in conjunction with Keen Aptitude (Denizens of the North page 348). Might I suggest adding a static PF or parry bonus passive power instead of 3 of those instances?
What were you going for? Looks to me like a very offense-built creature, with the exception of some passive powers. Skills include sneak and tracking, so I suppose it has ambush capabilities? Maybe have something that increases initiative in order to stay in a theme?
Thanks for sharing, it's great to see player builds, keep 'em coming!
