L20 protection warrior - what abilities to use without devastate and shield slam?

I've rolled a protection warrior and want to level in that spec to get a feel for defensive stance abilities even if fury or arms are faster. Already at Level 20, I feel I have more abilities than my level 80 paladin tank, but I am at a loss about which ones to use. I've read about the protection warrior "rotation" but it seems that, at least for single target fights, low levels miss the key abilities of devastate and shield slam. What should I use in their place? I am interested in all PVE encounters - soloing; AOE tanking and boss tanking. Although from what I have read, I seem to be ok for AOE - with demoralising shout, thunderclap, cleave and revenge.

Specifically, should I use disarm and rend much? Or could they replace shield slam and devastate as single target moves while I wait for revenge to proc? Or would the rage be better spent on heroic strikes, from a damage/rage point of view? Disarm sounds attractive, at least on bosses that are vulnerable but I don't know if rend is competitive in terms of damage.

And should I limit sunder armor to boss tanking for threat? Because although it appears like a forerunner to devastate, the lack of damage is profoundly unappealing for levelling.

Disarm is situational. If you're taking lots of melee damage, it can help, if a mob you're tanking is about to, or just started whirlwinding, throw a disarm up. There aren't many bosses in raids though, that you'll be able to disarm. Rend doesn't have a lot of utlity as a tank but at low levels, it might be okay.

As for Sunder, if you're fighting somethign that has a lot of health, sunder's not bad. Also, if you have a spare GCD, its worthwhile. Less armor=more damage=more threat.

Sunder armour is the poor tank's devastate. You use that until you get devastate and then you never use it again.

Shield slam is the tank's heavy hitter threat generator. You will probably be relying on revenge until shield slam comes along.

At your level, it will depend on what you are doing. Solo, rend is better use of the rage, but heroic strike might be even better. While tanking, remember that dps is not your job...threat and survival are. That is why sunder and disarm are good and rend is not. The threat from rend is not as good as sunder.

Thanks for the replies. I tanked Blackfathom Deeps at level 20 and had no aggro (or survival) issues, so I am feeling more relaxed. DS, TC, cleave and revenge are enough, it seems.

I did use rend a fair bit on solo mobs. I have virtually no other GCD moves for single targets and it does seem to be more damage/rage than heroic strike if I understand it right. ie rend gives you an extra attack in addition to your regular white melee strikes; heroic strike just bumps the damage of a white melee strike by 30%.

I did not use sunder armor much - the zero damage is just too unappealing. I don't fully buy the "damage is not your job" argument. That's a raiding philosophy. In a 5 man, the tank can make a significant contribution to damage.

Disarm seems nice but with a 1m CD is not something you can spam.

I am really liking how a prot warrior plays so far - after going through the 969 rotation as a tankadin, it is much more fun to try to figure out the best ability from my toolkit to use at a point in time.