Banded is 550, scale mail is 400.  Either way, the point stands. At least get a teleport, lock, or health pot.

If you are using towers you will be wanting staff of renewal favor item to get a tower farm up a lot quicker.

If you are not using towers, take blood of the fallen.

2 pure slam rook vids here: http://forums.demigodthegame.com/364806

don't get structural transfer if you are not getting early . Get amulet of teleportation instead then

in the beginning structural transfer can be quite good since you dont have monks (so better: 2. transfer, 3. arrows) but if you only have one general on your team, let him send you a monk for support. monk + 2 towers and a rook is really hard to crack in the first minutes. later on structural transfer is just useless. 10 seconds is far too long and good players will disrupt you for sure. so if you got monks then instead get slam. and if you got slam, boulder roll is a must have as early as possible! also with boulder roll you can help your mates. even if the fight is moving too fast for you. its range is really great!

if you dont have a monk structural transfer I is ok. later on dont get too offensive and use teleport, universal and sigil of vitality to escape instead of healing with structural. i wouldnt invest into wand of speed. the rook is so slow that even the wand wont help you much against any following demigod.

favor:

health, cooldown or mana.

mana is good for early game. if you dont have to fight against two enemys you can hold a lane without fighting too much directly. late game you will items for mana.

health depends on the item. blood of the fallen wont matter that much late game but early its quite good. though if someone lends you a monk dont get a hp item.

cooldown is great for mid and endgame. early you wont have enough mana for casting towers and slam again and again and if you run out of mana you dont have the hp to take out someone who has monks or banded+botf.

so generally i would take cooldown (staff of renewal). start with scaled (2nd your choice) and play rather defensively. means: build towers. take archers. if someone attacks the towers go in and slam. mostly they wait for the creeps and then attack your towers. thats the time for slam. even if they dont get hit, you kill the minions and they have to wait for the next wave.

I've noticed this too. Seems like up to about level 8 or so mana can be a big problem and spending time and money on mana pots is a disaster. I kinda wish that the Staff of Renewal offered more than +175 mana. I thought about saving up for the 1375 FP item that lets you cast free for 3 seconds, but that has its own drawbacks.

One problem with Rook is that in order to deal meaningful damage(to a DG) he needs to either put up a ton of towers(which takes time and space), or he needs to go deep into boulder and slam to pound out kills. I mean, they call him an Assassin, but really to me he feels more like a supporting fighter. He blocks off lanes and punches down towers but due to his short range and slow speed is often resigned to staring at nagging enemies.

Yeah, I've learned a bit from watching some replays already. I think my expectations of the game were badly skewed from playing single-player and not having played DotA. Still, even when I think I'm doing well it seems like I'm in the wrong place or I'm just not accomplishing a whole lot. I'll clog up a lane nicely and play back and forth with an enemy DG for a couple minutes and every time I try and move to strike they back up, then finally someone sneaks in(about 97% of the time this is a [censored] unclean beast)and I get slowed down and killed. It's like I can't figure out a way to stay on the flag and not eventually get caught by a gang tackle.

ya.. ganking is a huge problem for rook.  That's where you really need your teammates to teleport in and gank the gank, so to speak.

Generally, never go past the middle of the map, and if you do, make sure you have a tower farm to fall back to.  If you fight in the middle of 4-6 towers, you can boulder / slam and usually kill someone.  If you see 2 ppl running at you, you should start teleporting if you can't count on your teammates, or if you think you can run away go for it.  Your towers will do some decent dmg to them while you run.  A lot of tower / shoulder rook is standing near your towers, running when someone comes toward you and running back towards them when they back up so your towers and shoulders constantly hit them yet they cant seem to get a good reach on you.

Running up to an enemy flag without having set up some towers first is asking for a gank as rook imo.  Unless your teammates are there to support you.  But.. say you have towers set up, they come to gank you, and your teammates can tele behind them to your towers and they have nowhere to run then.  You can boulder roll them so they're stunned next to your towers while your teammates beat on them.. hopefully get off a slam.  Not too shabby then.  Very much a support hero tho.  Instead of minions, you have towers (I know some ppl play slam rook blah blah blah.. tower rook is support tho).

The people I play DG with, we call a rook alone "Free Gold".  Sometimes people speed stack a rook and they are harder to gank.  We call that style of play "useless".  Sure, we can't gank it as easily, but it can't actually DO anything.  Playing rook without teammates that you KNOW will tele in when the other team trys to gank you is, quite simply, asking for lots and lots of ganks.  

I'd go with Narmoth's Ring over Duelist's Cuirass, for several reasons -- it's only 1000 extra so if you hold of on Wand of Speed you can get it.  You lose a bit of mitigation, but have a bit more HP plus the +20 regen to make up for it.  Also it'll give you lifesteal, which will give you +1 HP for every single arrow from your archer tower in addition to melee damage and such.  Thirdly, the critical strike proc on the Cuirass won't be as useful to Rook as to others because of his slow melee attack.

And yeah Staff of Renewal is godly with towers, once you have the mana.  I haven't played much Rook lately but I used to have more luck as a tower build with both Plenor + Vlemish + Staff, especially since Bouldering people by the towers is great but a mana drain.

The Cuirass is really no good when it comes to damage.  5% chance for a 1.5 crit means, on average, that you get... 2.5% more damage per attack. That's pretty bad. Consider that at level 10 you may only be doing 300 dps of which 2.5% is 7.5 damage.  Big whoop. In comparison, the Slayers Wraps give +30 damage and 10% chance of 2x crit.  That's 30 + an average of 10% more damage from the crit changing your 300 dps into 363, a total 63 more damage!

(Note the above is assuming you attack once a second, the raw boost per attack will shift about a little depending on your exact attack speed, but this is generally about right).