'I am a good tank, look at my HP!'
This I've heard so many times and it's like a disease. As a healer, I would politely excuse myself and run furthest away possible. It may be good for sitting on the Fleet, such a huge pool will definitely attract some 'oh my..' attention. But that's pretty much it because as a real tank, you need to approach your stats differently.
Mitigation > Endurance
Without a doubt, mitigation is our priority. As tanks, it is our alpha and omega, since that makes us tanks in the first place. One can easily have a Commando with nearly 35k HP, wearing heavy armour – does this make them a tank? No. Same for us, having 42k HP and heavy armour doesn't mean that we are good tanks (even worse if it is a Shadow tank in light armour!). So forget about Endurance and start looking Defense rating, Shield rating and Absorbtion rating. This site (many thanks to Rurik!) provides a table which allows you to quickly see what distribution should you aim for with your current stat budget.
Armourings / Mods / Enhancements (2.1 patch)
To begin with the essential, we have to avoid all the Endurance heavy modifications, and yes, that forces us into the expensive mix & match game. The obvious exception to this are Armourings where we simply pick the Endurance heavy ones, because threat is not an issue and therefore we don't need to go for the Str/Will/Aim heavy ones. So for Shadows, Advanced Force Wielder Armoring 31 is the one to stick to. Regarding Mods, we aim to get the ones with the most mitigation stat. Advanced Reinforced Mod 31 or Advanced Robust Mod 31 are the current BiS (Best in Slot), everything else is only a worse alternative. As for Enhancements, the situation: Advanced Bulwark Enhancement 31 and Advanced Bastion Enhancement 31. Enhancements with higher Endurance are the least desired option. Also, Accuracy Enhancements are not our aim, because threat is not an issue even with the basic 94% Accuracy.
So to sum up, the formula always remains the same: Avoid Endurance-weighted modifications and look for the mitigation.
Augments sometimes serve as a 'patch' for DPS classes to reach the cap; boosting whichever stat they are missing when it's not provided by the gear itself. For us tanks, the situation slightly differs, because we shouldn't be missing anything (such as Critical, Surge, Accuracy). We use augments to balance our mitigation so that we don't waste any of the three. As mentioned above, use the table to see how to properly balance your mitigation stats in order to avoid wasting them because of diminishing returns.
These are the augments we want: Advanced Redoubt Augment 28, Advanced Shield Augment 28, Advanced Absorb Augment 28.
At the end of the day, you get enough Endurance from the gear, you will always use Endurance stim and have the Trooper buff, so you don't need to worry about being under 37k HP which is entirely enough. Having over 40k HP doesn't help your healers if you take seven 15k hits in ten blows, while having 37k HP and taking only six 8k hits does. And that is the reason why we don't want to sacrifice mitigation in favour of Endurance.
There will be several similar articles coming up soon to sort of sum up the basic aspects of shadow tanking before I go into more delicate matters. After all, I still want this blog to provide a complex overview of shadow tanking. Until then...