How would you describe tanking is as a Shadow?
So first off, tanking is a little different that in wow. There are a lot of mobs that shoot from range and are basically unmovable. Packs are often spread out enough that no one ability you have will hit them all. So it tends to involve a lot of movement and/or a lot of CC to control a pull well. Furthermore, several of the cc's are "last 60 seconds, on a 60 second cooldown" so if it gets broken early it can not be reapplied.
Tanking as infiltration:
Use tanking stance. Often you get to stealth in to do the initial pickup, which can be useful since it gives you the option of doing a "sap" for CC'ing one mob. Open up from behind on one mob relying on your fast energy regen post stealth to get you energy back, pick a central mob and force breach (which is an AoE in tank stance). At this point you probably have everything on you. Taunt any thing that isn't. Move as central to the group as possible and hit the swipe-equivalent skill that hits every mob in 10 yards -- its cheap for infilitration. If any mob gets pulled off you (unlikely but happens occassionally) taunt it back.
Tanking as Kinetic:
You have a lot of different damage reduction cooldowns. There is a ~10 second cooldown that gives you +20% shield block chance with 8 charges for 15 seconds, that you basically want to use either when the buff is about to drop or when you are down to 1 charge. You have a a reduced damage cooldown that is 5 seconds of immune to force or kinetic attacks on a 30 second cooldown. You have a longer cooldown self heal. You also have a talent that makes spinning kick not require stealth to use -- which means you have a knockdown on a relatively short cooldown; so far I've found it to work on everything except bosses but including some things that seemed to be stun immune and its a good way to give the healer a few seconds to catch up. You also have a buff you stack up to 3 times, that when fully stacked causes project (a channeled attack) to also heal you a reasonable amount -- you can dodge/parry/shield while channeling.
You have a lot of AoE. You have 2 separate "hit everything in 10 yards of the targetted mob" short cooldown abilities, each of which applies a different damage reduction buff (one is -5% hit, one is -5% damage) that you want to keep up on as many enemies as possible. And if both of those are cooldown, you have a melee range AoE strike with no cooldown.
You have a lot of energy regeneration. There is a +30% energy regen talent. And you get 2 energy back per attack blocked or shielded, which adds up fast.
You have a "death grip" equivalent -- but be warned it has a large minimum range so its often hard to use.
Your sprint is on a reduced cooldown and is talented to remove movement impairing effects, so you can use it to shoot around and pick up problematic mobs or move out of bad stuff.
Starting the pull is casting your +block% skill and then moving in, throwing a rock at one target off towards and edge (note the rock has travel time, so you can often cast it and then retarget before the mobs actually are aggro'd) and then quickly swapping targets to a one that is central and doing one of your AoE's to pick up everything near that mob. If group is clustered, do the other AoE, otherwise swap targets again to another chunk of mobs and use it there. Use the deathgrip equivalent if necessary - but I found I don't use it a lot. Especially with spread out range strikers, I find myself running a lot and using various 10 yard range attacks to build threat.
On bosses, things change a bit. You become focused on using your cooldowns a lot more. Always keeping +shield block up, rotating through your reduction and self healing cooldowns at appropriate times, and doing whatever the boss mechanic is. Single target threat is a lot of keeping the debuffs up on the boss, throwing rocks, using cooldowns and the occasional other ability.
Comparing the two, I think that the infiltration tanking is probably simpler but has a lot less tools to let you turn a marginal situation in to a win. And I've definitely seen bosses in level 50 content where infiltration tanking would not be viable without over gearing them. However I found it good for leveling and for non-50 instances.
Tank spec tanking (kinetic) is pretty dynamic. You have a lot of options and it there is definitely the ability to be smart and make yourself more successful. It is rare that you feel energy starved.
One other change worth mentioning for people who are used to thinking of wow shield tanking. Hits are done different. Its a 2 roll system. The first roll determines if it is a crit, miss, parry, or hit. The second roll determines if it is shielded. There is no way to become crit immune. I _think_ that it is conceivable to get it to where you push "hits" off the result table and only get crit, missed, or parried. This means there is not a need to stack +shield rating to get to some 'cap' value.
