Tactics: The Way of the Destroyer
After some analysis and playtesting, I believe that the following guidelines are key to playing a successful Barbarian.
1. Be aware of how you destroy.
The first step to playing a successful Barbarian is identifiying what the particular build does the best. This depends on the combat style you have chosen, which I will detail as follows:
Rageblood VigorThis build feels and plays like a Brute; you're big and tough, and you deal a whole lot of damage. That means you charge into the frontline, taking some of the heat off your Defender (also known as "off-tanking") as you hew into enemies left and right. Occasionally, though, you may want to use the mobility you are afforded by charging to get through the enemy frontline and beat up on the squishiy target. Remember that you have no marking ability, so you can't protect the squishies in your party.
ThanebornThis build also functions as a Brute, but it has a strong hint of Leader; the array of buffs and debuffs you carry can make life a lot easier for your companions. You like being on the front-line as well, but you're not equipped to be in there as long as, say, a Rageblood, so you'll have to work more closely with the party Defender.
ThunderbornThis build is an interesting mix of Brute and Controller; you have positioning abilities galore, and plenty of AoE-style damage as well as solid single-target swings. Like the Rageblood, you can "off-tank", so the front-line is your place to be. Additionally, you are very proficient at dealing with minions, so getting swarmed happens less often to you.
WhirlerThis build diverges from the others in that its play style is more of a Skirmisher than anything else; you weave in and out of the fight, dealing out damage indiscriminately to anything that you happen to come across along the way. Like the Thaneborn, you're not as tough as some of the other Barbarians, so the Defender needs to help keep your nose clean. Also, your emphasis on area damage means that if you can catch enemies in clusters, you can maximize your damage potential, so look for allies to help you place enemies where you want them to be.
2. Crush 'em.
A Barbarian is a Striker first and foremost. That means your responsibility is to get to the most annoying enemy, and cave his skull in. The order in which the following points are illustrated indicates the priority you should place on the aspects that entails.
Smack them around.Damage is one of your strong points, and you should emphasize it even further. There is no control like bringing your enemy down to 0 HP. This means that damage should be your primary (not only) consideration when evaluating a choice. Anything that boosts accuracy, damage, or allows you to squeeze off multiple attacks in the same action (or even outside your turn) is particularly prized for damage output.
Get in their grill.All the damage in the world won't help you if you can't get to your opponents, so look for abilities that help out your mobility. Barbarians are one of the most (if not the most) mobile pure Melee classes in the game because or their charge-happy bent, so take advantage of this to get where you need to go.
Hobble them.Another way to hamper your chosen opponent is via conditions and other maladies. Barbarians are a bit lacking in the more traditional action denial status effects, such as dazing or stunning, but make up for it with a multitude of mobility denial effects, such as knocking prone, immobilizing, pushing, or slowing. This limits your opponent's options, and is particularly valuable against enemies that are trying to get to your back rank.
3. Get tough.
Because of your strong damaging potential, you will be a prime target for (usually unwanted) enemy attention. Although you are overall more durable than other Strikers, even you can't handle getting hit by everybody all the time. So, some suggestions for staying on your feet:
Move around.If they can't reach you, they can't hit you. You have the virtue of being able to initiate an assault from afar, thanks to your charging potential, so use that to your advantage. Move about while picking off individual targets, unless you get a prime opportunity to take out your target by charging in. If you do, at least try to make it easier for your party to get your skillet out of the fire.
Tank up.They can't hurt you if they can't hit you, so high defenses go a long way in keeping you up and running without drawing time and resources away from the rest of the party. This has a caveat in that there is a limit to how much offense you should sacrifice; you are a primarily offensive character, and that is what your selections should be geared to, for the most part. After that has been taken care of, invest in your defense. You are more durable than other Strikers (you're probably more durable than some Defenders as well), so this is a bit less of a priority than it is for others of your role, but don't ignore it.
4. Look out for your teammates.
You may be tough, but you have a tendency of getting in a whole lot of trouble in combat, so you might wanna stay on your buddies' good sides. Defenders can wade into the melee with you and watch your back while you beat someone up, Leaders can keep you up and running after you've gotten yourself in a jam, as well as turn you into something even more unstoppable, and those fancy Controller folk can deliver you your opponent bound, gagged, and tied up with a large bow. Help them out when you can, even if it means taking a gamble; gambling is kind of what you do for a living. And remember; if you help them, they usually will help you.
All this being said, don't make the mistake of believing that the rest of the party is your personal squad of minions, ready to do whatever you suggest at a whim just because you said so; such has been the downfall of many an arrogant Striker.
5. Apply force judiciously.
Having a good understanding of a given tactical situation can save your party more time and HP than any damage combo you (or anyone else) can cook up. Learn when to stick to your guns and fight conservative, and when to gamble more resources to end the encounter faster.
Barbarians in particular face an interesting conundrum in that their Dailies are Rages, and will usually hand out a buff until the end of the encounter. This can tempt you into front-loading the Rage as your first attack of the encounter. Unless you're sure that it's a boss fight, resist that temptation; try to gauge the strength of your opponents. If they offer up some stiff resistance, fire away. If not, you just saved yourself a Daily power, which you can unload on the next encounter as a Rage Strike for a whole lot of damage.
6. Balance specialization with versatility.
A Barbarian is fairly straightforward in his methodology: charge right up to it and hit it over the head until it stops moving. Look out for ways to expand your options, so that you don't end up being a one-trick pony. Don't sacrifice too much for versatility, though; you want to be good at what you do, and that mostly involving beating things over the head with heavy objects.