I've been tanking in this game since shortly after it went live. My main is an invulnerability/super strength tank (currently vet level 100 on HC), I've also played ice/ice, stone/stone, fire/fire, shield/mace, SR/SJ, radiation/radiation, willpower/psi tanks to level 50+, and I'm currently working on an electric/electric tank. This post is based on my own experiences, as well as questions I've had during that time, and watching years of tanks play during Tanker Tuesday events.
Any AT can tank, at least once, though how long they survive depends on the situation, their build, the enemies, and the environment. I won't be getting into which is "better," I'll limit this discussion to explaining aggro mechanics, basic "tanking" techniques, etc. Also, when I say "tank" here, insert your favorite AT you think can tank, it's pretty interchangeable. As far as the tanker AT goes, I think the best way to explain what a tank is is that it's a melee range controller, whose job it is to reposition mobs into groups to make team PBAoEs and ranged AoEs more efficient.
Basic aggro mechanics
Aggro in the game is based on many things. I think it goes kind of like this. Can the enemies see you? If so, they attack you, until a better target presents itself. If players generate "threat" to mobs, from experience, it's in this order: Are you the first visible? If so, you take the alpha strike. Controllers very quickly rise to the top of this threat list, followed by damage dealers. Tanks try to insert themselves into this threat list, at the top, hopefully, to protect the team. As a tank, I've found it's hard to pull aggro off a controller once they've pissed enemies off, more so than damage dealers. So, I think enemy threat priority goes like this: controller, tank, damage dealers, everyone else.
Aggro management
Tanks, and, brutes, have an inherent ability called gauntlet. It's an AoE taunt that hits up to 10 targets for tanks (brutes may not work this way).
Gauntlet has a taunt component (magnitude and duration), which forces the target to attack the tank for the duration of the taunt. Magnitude determines where on the threat list the taunt overrides current aggro of the mob. The most useful component of gauntlet, however, is a fairly substantial range debuff, which combined with taunt, forces the enemies to close on the tank.
Most tanks have a "taunt" aura, a PBAoE damage or effect aura. These pulse at regular intervals, typically once per second, some more, some less. For tanks, these pulses also have gauntlet, so once enemies get into melee range, this aura effectively glues foes to you, and makes it very hard to pull them off a tank. Trouble usually happens at the parameter of the PBAoE, where aggro can be peeled from the tank.
Aggro cap--Aggro is capped at around 13-16 (I forget exactly which). What if I told you you could get around this through careful manipulation of the "threat table?" More on this later.
Finally, a word about the taunt power. Taunt does not a tank make. This is important, so I'll say it again. TAUNT DOES NOT A TANK MAKE. Taunt is a tool, among many, a rather poor one, that I rarely use, but this opinion is in the minority. It's slow to animate, and it only (auto) hits 5 targets, with no gauntlet component. A tank has many attacks, PBAoE, some have a ranged attack, all with gauntlet. All extremely more effective than taunt at holding aggro. Taunt is for the periphery, but my go to is a attack (PBAoE or ranged) if I have one. If you're only using taunt to tank, you'll do it poorly. You have so many other tools that are much more effective, use them first, use taunt to pull aggro that escaped you back from your teammates.
The survivability "triangle"
Regeneration, resistance, and defense form what I call the survivability "triangle." Damage output can be considered a fourth leg, if something is dead, it can't hurt you. Various powersets provide varying amounts of this triangle. Some are easy to augment with IO sets, eg, defense, while regeneration and especially resistance are difficult to significantly augment through IO sets. You'll frequently see soft-capped defense on many ATs, boosting resistance more than 10% is very hard to do via IO sets, while regeneration is somewhat in between. Defense is fairly easily debuffed through lethal and radiation attacks, quickly stripping your tank of their primary survivability leg. Regeneration and resistance debuffs are rare, and where they exist in the game, are also low in effect.
Tanker powerset taunt auras
Some tanker armor powerset taunt aura provide an additional benefit per foe in melee range, some of these can be huge, making the difference between an unstoppable God, and a pleb.
Invulnerablity: Invicibility provides +defense per foe in melee range. Huge benefit, it's what turns your squishy tank at level 17 into a beast at level 18, susceptable to defense debuff
Willpower: Rise to the Challenge provides +regeneration per foe in melee range. Another huge benefit
Radiation armor: Beta decay provides +recharge per foe in melee range. Weak benefit, the per foe buff is low, and the overall cap is low. Compared to the other tanker auras, this one contributes little to survivability
Shield defense: Against all Odds provides +damage per foe in melee range. Decent benefit, reduces enemy damage, buffs yours
So, what now?
I've explained threat generation, basic aggro management, and survivability. So you may be asking, "So how do I tank?" Like I said earlier, for me, tanking is a mindset. I find it hard to not try to tank on every AT I play, with varying results. I'll try to boil down this mindset.
Aggressiveness--the best tankers I've seen in the game throw themselves into danger, regardless of the threat. I typically test my tanks to destruction as they level up, especially if I'm playing a new powerset for me. I learn what my tank can take, and what they can't, so I can tank on the edge of survivability. Remember, your job is to take alpha strikes, reposition mobs to maximize team damage output, and keep your eye on your team's health, so see where aggro has bled off on the team, and get it back. In my experience, timid tanks are the most frustrating, they are difficult to teach, and it's an extremely bad habit that is difficult to unlearn. Don't learn it. What is a timid tank? One that hesitates before engaging, waiting for the team to show up before jumping in. You could be using that time to gather aggro and group mobs, your team will catch up.
Also, tanks don't run. If you die, your team dies, most of the time. If you run, you likely die, and so does your team. Tanks hold the line at all costs.
Herding--your primary job is to reposition mobs for your team to annihilate. Here, taunt will simply not cut it. You must use gauntlet, for its taunt component, and more importantly, the range debuff. Run into a mob, weave through them so you hit all foes in the mob at least once with your taunt aura (preferably twice). Move to next mob, repeat. You should now have aggro on two full mobs, all looking to pile on top of you. Aggro at this stage is pretty weak, so your team will have to be patient until they all pile on top of you. Lock down aggro with a PBAoE attack, and then the team can unload at will. Controllers, please try not to lock down mobs during this process. It results in a bunch of spread out mobs
whose threat table you will quickly rise to the top of, and it's difficult to unscramble that egg. Don't do it. You only have to keep your finger off the trigger for a second or two. Trust me, the wait will be worth it, or, you will likely face the wrath of multiple enemies who will kill you. Your choice.
Remember I said earlier it's possible to bypass the aggro cap? It's based on the threat table. Even if you're over the aggro cap, if you've hit a foe with your gauntlet, you go into their threat table for the duration of the taunt. When foes that are within the aggro cap die, if you're still on the threat table of other foes, they will come to you once a spot opens up in your aggro cap. I think most taunt durations in gauntlet are about 15 seconds,
so you will only loosely hold this virtual aggro and not for very long, and it's easily overpowered by your teammates, but it works nonetheless.
Some mobs have mostly ranged attacks, and the range debuff in gauntlet isn't enough to get them to pile on top of you from this "brush pass." For these, you can either marinate them in gauntlet long enough to debuff their range enough for them to follow you, or you can find a spot that breaks line of sight, forcing them to come and pile on top of you, or both. Breaking line of sight isn't always possible though. Rikti on a mothership raid require both gauntlet marination and line of sight breaking to effectively herd your aggro cap(+) to the bowl.
Finally, there's nothing wrong with fighting mob to mob, and forgoing mass herding. If the situation, environment, and foes warrants it, herd away. If it's slowing things down, don't bother.
Multi-tanking
At times, you'll have multiple tanks on a team, each with their own aggro cap. One should be the primary tank, first to go in, while the others support and feed that primary tank with additional mobs. Don't "cock block" your fellow tanks by stepping on their aggro train while they are herding, get your own! Bring them back to the primary tank, and when you and your team have whittled away most, leap out and go grab the next group, a technique callled "leap frogging." Your team can mob up the stragglers, by alternating primary and supporting tanks, with support tanks feeding the primary, and swapping roles, you can steamroll through most content.
Taste the rainbow
Finally, you have a full tray of inspirations, and they drop all the time. Keep a break free, for when you've been end drained and lose all your toggles, maybe a couple of blues, maybe a row of purples/oranges. Don't be that guy/gal who dies with a full tray of uneaten skittles.
Conclusion
I think that's most of the basics. Learn your tank as you level up. Test to destruction. Be aggressive. Use gauntlet! See you next Tanker Tuesday!
