start out with scaled helm(+ mana +mana regen is important) + 2x telescrolls + 15% movespeed circlet(favor) and go take a tower + wave (hammer 1 hit wave) now your level 2.
1:hammer slam
2: archers
3:tower
4:slam
5: lazer/tower/boulder (depending on game)
6: see 5 but make sure you have lazer
7: hammer slam
8: tower/catapult
9: make sure you have boulder else get more towers/up damage if pushing
10: hammer slam
11: second level of boulder
ensure getting insane amounts of mana regen either by heart or an early vledemich or whatever its called helm (15 mana regen is nothing to joke about)
not hitting boulder/hammer when their close is really shameful ... i feel bad if i miss , and hammer slam is not impossible to land just dont hit straight on them, if theyre running away from your tower intercept with a hammer , now if they want to juke they need to go back , take side damage from hammer + towers + archers/lazer and you can chase them down with archers/lazers in a lot of cases .
use your teammates stun if needed to place a hammer .
if they keep away from you and you get time of start putting up a grid , 1 hit the creep wave and start hitting the tower with
your creeps throw another hammer when next wave is underway ( make sure you hit the tower) and repeat the process . if you have heart you can push 1-2 towers per min and they will have to come to you , always maintain mapcontrol and tele out if you feel a gank coming.
rook is really powerful , being able to do alot of roles at early/mid/lategame , watch out for erebus and tower spam regulus
quick edit: ive lost 1 game total with rook and that was because my teammate feeded 10 kills then left after 7 mins