Janook's Rook Build, Version 2.
My original build is posted here: http://forums.demigodthegame.com/366951/page/2
I have taken into account comments from other players. Additionally, I now have several dozen competitive 3v3's under my belt playing rook. I've seen what works, what's important, and made some small adjustments to my build to make it more powerful.
Special thanks to KingSlet for his advice.
The biggest difference is getting Arrows at level 2, and basically pushing every skill back by one level, including boulder. The reasoning behind this is you simply do not have the mana to be using towers and hammer early on in the game. Arrows add significant damage at 0 cost of mana and in my experience have greatly helped me hold lanes against demigods early on.
I have to say that this build is very much not static. It is so important to judge the current situation to decide what skill you will get. I cannot stress this enough.
First 6 levels:
1 - Tower
2 - Arrows
3 - Hammer
4 - Tower
5 - Hammer
6 - Boulder
At this point, you must make a judgement call, whether to prioritize towers or hammers. It depends mostly on the pace of the game. If your teammates are consantly in heavy engagements, and you need to teleport in for kills, you must have your hammer ready to dish out some serious damage. If the game is a little slower, you can focus on lane control and a slow tower push. If it's really slow, you can forgoe hammer for a while, opting to upgrade towers and shoulder weapons all the way to your trebuchet, allowing you to set up tower farms and sit back while the enemy towers fall.
Usually, I go with this:
7 - Tower
8 - Hammer
9 - Save
10 - Tower, Hammer
11 - Boulder
12 - Tower of Light (Shoulder)
13 - God Strength - If the game is slow, continue upping shoulder weapons for your trebuchet
14 - God Strength
15 - Hammer
16 - Boulder
17 - God Srength
18 - Stat - I have found Trebuchet / Poisoned Arrows to be pretty useless late-game. But if towers are still up, or you are still in situations where you are chasing fleeing demigods, by all means, hold off on stats and get them.
19 - Stat
20 - Stat
Favor Item: Staff of Renewal
I still maintain that this is the absolute best favor item for Rook. It will allow you to use your hammer/boulder one additional time in battles. That is a whopping 1.7k damage to 3 demigods late game. This is huge. It changes the course of battles, every single time. Additionally, as I maintain that getting tower level 10 is usefull, this will allow you to put up those 8-tower farms significantly quicker.
Equipment:
Scaled Helm, Banded Armor
Vlemish - Remember, early on, your hammer is weaker but your towers are strong. I emphasize mana early on to maintain a tower farm and keep yourself out of engagements.
Nimoth Armor
Unbreakable Boots
Scaled Helm -> Plenor Battlecrown
Banded Armor -> Hauberk of Life
This equipment is heavily synergetic with your play style. Early on, you have a small mana pool but good mana regeneartion, this will allow you to continuously throw up towers for long periods of time. Later, after getting Plenor and Unreakable, you have a larger mana pool, allowing those bursts mana usages of boulder + hammer.
Your early equipment is extraordinarily important. You will be useless without a good mana pool. Strongly recommend convincing your allies to purchase the expensive Cit upgrades (Currency I, Exp I), and perhaps you getting FS1. Even the 600 gold for FS1 can be brutal. I played one game where I bought both Curr 1 and Exp1. By the time I was caught up in gold to be competitive, we were 2 war ranks down. This was with a strong team. You will not be able to hold flags or even farm properly without your early equipment.
Play on.
Do not try to boulder+hammer early just to hold a lane, unless it is absolutetly necessary. It will eat so much of your mana.
You are to sit tight, throw up your towers, and level up.
Your biggest threat is getting ganked early game. Take care. Do not overextend.
Never go after deep flags unless you know your allies will teleport in to take care of you.
Wait, Max towers? Seriously?
Yes. Some players maintain that towers are useless late game. I disagree.
Setting up a tower farm in a port you are trying to take back significantly tilts the odds in your favor.
Setting up a tower farm to assist in a front-door push significantly tilts the odds in your favor.
And, if the game is slow and you took your trebuchet upgrade, setting up a tower farm will allow you to sit tight and bring down the enemy towers.
Listen: Tower 4 does several things. Yes, it allows you to put up 2 extra towers. More importantly, it boosts tower HP and damage. And most importantly: It halves the cost of throwing up towers. This is huge. This is... HUGE. If you have your two mana helms (which you do), you can put up towers indefinitely. Forever. You will never run out of mana. Also, you now have the mana reserve to be spamming boulder + hammer for several encounters before refueling. And between encounters, what are you doing? Towers.
The best way to get kills:
I have found this Rook to be a particularly great bait. Throw up a strong tower farm, run in for a flag. The enemy will come teleing or running after you. Flee behind your towers. If there are two demigods chasing, they will usually feel confident enough to chase you into your towers. Your allies will tele to your towers. Sigil, turn, boulder, hammer, they are dead. I have used this against noobs and pros. The rook just looks so juicy. 
I do not feel like writing an in-depth strat about this build right now. Suffice to say, this is a strong build if played properly. I would not recommend this for new players, or players not used to constintely re-asseing there exposure. You must be extremely map-aware to use this build, and have plenty of faith in your teammates to tele in for ganks, over and over and over again.
Comments welcome.