Ok, the Rook is not as overpowered as mentioned. Just a few things to make him balanced imo.
The Smash is fine, its so EASY to dodge it - ok, AI can't, but they still got AI-problems, and AI will never be as good as other players. It's a hard skill eraly game.. later on, the only thing you'll get mostly is the lower AE-Dmg.
The "Structural Transfer" is the strongest skill he has - in terms of power - deals huge damage against buildings, heals himself for tons of hp + cannot be interrupted after he started the attack (tried that one.)
The small towers he can produce.. aren't that good, they do no serious damage (~60 per hit) have long cd. All they have is a decent amount of HP. But you can have them only on lv 10.
The additional cannons are ok, but nothing to scary. And the Roll just got a too low cooldown. 10s => 15s would be ok.
And last but not least.. maybe lower his HP a tiny little bit, at level 15 he got nearly twice the lifepoints of Remulus or Torchi, i think +50% more than the others fit him. Ah, and something you shouldn't forget => Rooks attackspeed is to high, it doesnt fit with the 2.5-3sec. tooltip. If this gets fixed, his damage output will decrease significantly i guess.
Edit: I dont think, the Boulder should be slower. At long range, its nearly impossible to hit any decent players - due to the cast time. Also he has an really obvious cast animation while casting the boulder - so you get a free warning. Btw, if a Rook player manages it, to come close to you (with his craaaazy movespeed) he should be able to stun you with a decent chance. I mean Rookyboy will get focus fired alot in real games imo, due to his huge sizes.
So long, Aspartem