In Final Fantasy XI parties, you will find that there is a certain "build" as to how a party is constructed. You will need your damage dealers, you will need support and healing mages, and finally, you will need a "tank".
A "tank" is a position in a party that requires that member to maintain the attention of the monster being fought so that damage is focused solely on that person. It can also be used as a verb, such as "to tank the monster." The actions that you do, be it damaging the monster or healing yourself, will increase your "enmity" (Square-Enix Term) or "hate" (common fan term) towards the monster. The idea behind this is to have the highest amount of hate on the monster compared to the rest of your party members. There are a few basic key things to know, and thus that will be the purpose of this post today.
The Very Basics
Before you can really tank a monster, you obviously will need to be able to take the hits and hold the hate. Because of this, certain jobs at certain levels can only tank a monster reliably enough. Due to the nature of this being a beginner's guide on the subject, I'll only be covering the early levels. Later on though, tanking gets a bit more open and there are a ton of different options.
Any job can tank depending on situation. The idea here though is to tank effectively to the benefit of the party. Just because I said any job can tank doesn't mean that any job can tank in all situations. With this in mind, please note that if you have a somewhat undesired job for the situation for tanking, take that into consideration as that can decide if you get XP or no XP at all. I'll cover XP group mentality later but for right now, avoid trying to bring in something that won't work.
Throughout the levels, you will see that PLD and NIN are the most preferred jobs for tanking in an XP party. There are also some other options like SAM and WAR but it will be PLD and NIN that will tend to be the best at the mid-levels. Regardless, mostly all tanks will sub WAR for their subjob. Why? Because of the WAR's ability "Provoke."
Provoke: A Tank's Friend... but a big misconception too
So, what does provoke do? Well, it's a level 5 ability that you learn on WAR and it is an action that doesn't do damage or debuffs or anything. What provoke does is give you a large amount of hate. So, you provoke once, you have that large amount of hate, and you're set, right?
That seems to be one of the biggest problems that I see with upcoming tanks. They assume that provoke...
A. Make the monster instantly come to you, no matter what the situation.
B. Has a huge amount of hate that will keep you at top of the hate list forever.
C. Is only used to pull hate off of the mages and that's it.
Without getting into technicalities, the best way to use provoke is to use it every time you can. The recast on provoke is 30 seconds so you should be provoking every 30 seconds. Why? Lets go into the technical stuff!
After years and years of research and figuring out the huge enimga that is enmity and hate, we have discovered that hate has two values which are then summed up into your total hate. Those two values are "Cumulative Enmity" and "Volatile Enmity."
Cumulative Enmity (CE)
CE can be best described as actions that build up slowly but only goes down when you take damage. Stuff that can build up slowly would including healing and damage from attacks or spells. This number will constantly go up and down based how much the mob is hitting you to the ratio of how much damage or how much curing you're doing. There's a little more to it such as debuffing and such but this is the bare basics of that.
Volatile Enmity (VE)
VE can be best described as actions that spike up your hate to a large level but the value decreases greatly over time. The only real influence to how fast this drains is time. As time goes on, the enmity effects of the ability or spell you did will decrease until you add more to this value or it hits zero. Unlike CE, taking damage doesn't do anything to this. Provoke is an example of an ability that increases your VE.
With that in mind, you'd want to keep provoking to keep your VE up. Especially at lower levels because all you will have for VE is Provoke, the rest will come out of your CE.
Now that I covered that, lets look at what options each individual job has for tanking.
Warrior can tank... but they also "can't" tank at the same time. What I mean by that is that WAR can tank things and it can get the job done at lower levels (again, I want to reemphasize that this isn't touching merit parties or anything). However, they end up being a huge sink on MP and unless a party is set to really help the WAR tank or if the WAR isn't properly geared for tanking, chances are that XP will be very slow. However, it can be possible for a WAR to be a great tank if the situation is right.
Tank has two major hate tools: Provoke and its own damage. Provoke, again, is VE that is on a 30 second recast timer. Abuse that, it helps. Next is that it has damage to back up any sort of CE required. I would suggest having a Great Axe for this situation.
SAM is on the same boat as WAR... at least until 35. Before then, avoid being the tank for the party as it will be very difficult. Once you hit 35 though, you get an ability called "Seigan." Seigan is a stance like ability where you can only have Hasso (which increases your stats) or Seigan up, not both. Seigan gives you an upgraded "Third Eye" ability, which SAMs use to anticipate attacks and negate or counter it. Third Eye may block more than one attack with Seigan up. However, it could be 1 hit... it could be 20 hits... it is completely random. Third Eye is on a 30 second timer when Seigan effect is up. If the first hit takes out Third Eye, you will have nothing to protect you for awhile. If you get hate or you're tanking something that does a lot of damage and you're not prepared for it, it can be fatal.
PLD has many tools that it can use to get hate. Not only do you have Provoke from /WAR, you also have Flash, Sentinel, Shield Bash, Rampart, and the ability to cure yourself and along with other things. PLD is a straight forward job and it is all a matter of balancing out your abilities so that you can keep your VE up constantly and build up your CE while you're at it. They also have many defensive traits such as using a shield to negate a percentage of damage.
I'm not gonna lie: NIN is a hard and expensive job to tank with. Pre-37, NIN will have a hard time tanking. Not only do they lack a second shadow spell (Utsusemi), they also get hit hard when they get hit. However, once a NIN hits 37, tanking becomes so much easier as now the defensive option is more reliable and at 40, NIN gets some new spells to help keep hate better. Adding onto the fact that NIN can do a bit of damage themselves, NIN can be a great tank but it will be a huge gil-sink considering that each spell requires a ninja tool to use. While cheap, you will need a LOT of them.
Now, there are other jobs that could tank pretty "ok" such as DNC or BLU, but from what I've experienced, none of the other jobs really did that much better compared to these jobs. So, I wouldn't recommend them but don't be afraid to try them out as long as you know what you're doing and not getting in the way of other people's progress, as I'm sure you'd want them to do the same to you.
That about wraps it up, I hope most of you out there had a great 4th of July. Talking about fireworks though... I believe there's a summer event coming soon in FFXI, take a good look out for that one!