Banner

hands down

Depend of your build, if you're in lack of survivability, use magma armor if you're in lack of controle or aoe damage use Banner.

I guess you'r right, i'l go with banner then i can also combo it with talons.

@Lazyness is on the right track.....When a tank loses agro, due to lag, overtaunting or simply the boss mechanic resetting the taunt timer an aoe damage ability is one of the best ways to gain agro without actually taunting (if it bugs or boss immune etc.). Banner is great for this. Shifting banner specifically because agro is your objective not dps. So if the boss leaves the area you can reapply the standard.

Magma Shell will be your best bet if you're having mitigation issues with your gear but is not necessary when your gear is at par. obsidian shield, spiked armor and green dragon blood will also help with mitigating.

Finally, most big baddies are immune to talons....so don't bother on the boss fights. Your better off applying ash cloud (cinder storm morph) and something like caltrops from the pvp skills. Inhale is good aoe for agro as well.

War horn
Most of the time, standard and magma armor aren't needed, so in these case war horn boost dps and healing. I use war horn and standard (when I need to dps alone and keep aggro, like when dps are dead).

Ah, perhaps. Now he will know that he need rank 4 for alliance war
If I can't have war horn, I prefer standard then magma armor.

Yes my DK is still low level but your advises and suggestions are highly appreciated specially about the war horn. Now i pretty much know what to do up to mid level. Thanks guys keep it up

yeah it mostly depends on what your group is like and what content youre doing. Like standards and meteor is best for Vet dungeons and DSA but sometimes I find myself using warhorn some my fellow DPS can put out higher numbers or barrier for the extra protection. The only time I actually use magma is when i am in a trial's group with bad healers. hope this was helpful!

As a tank, you'll need a lot of different ultimates in different situations imo.

For example, when we are doing vDSA, we'd like the tank to use different ultimates on different stages.
Tank is using warhorn, banner, barrier depending on the stage.
Of course this will all depend on your group and the playing style, but it's just to make clear that you will end up using a lot of different ulties eventually.