Diablo III- Skills Article VI: The Barbarian, Primary Skill- Frenzy

Frenzy: Deal 110% weapon damage to one target.  Gain a 15% speed boost to Frenzy that stacks up to 5 times (maximum 75% speed boost).  Generates 3 Fury.

Work it harder, make it better, do it faster.  When you need to hit it stronger and more and do it now, Frenzy is your choice.  While it’s interesting to try to use effectively in large-number combats, the place where Frenzy really shines is when fighting a boss.  If you usually use Cleave and are about to fight a single massive enemy, switch to Frenzy- you’ll like it better.  Not only will you generate Rage faster, the damage quickly increases beyond Cleave’s for smashing a single target into the floor.

Sidearm: Deal 110% weapon damage to one target with a 25% chance of launching an axe at a nearby enemy, dealing 110%weapon damage to that enemy and any other enemy it hits.  Gain a 15% speed boost to Frenzy that stacks up to 5 times (maximum 75% speed boost).  Generates 3 Fury.

Sidearm is one of your more bizarre toolbox effects that you can get for the Barbarian, and makes Frenzy -especially- interesting in mass combat.  With the help of Sidearm, Frenzy can compete with Cleave for mass-combat damage in the right setup, and with nearly anything for sheer WTF factor.  Sidearm gives every Frenzy attack a shot at throwing out an axe a la Weapon Throw that pierces through things it hits in order to keep going to its actual target.

Triumph: Deal 110% weapon damage to one target.  Gain a 15% speed boost to Frenzy that stacks up to 5 times (maximum 75% speed boost).  If the attack kills what it hit, you heal 8% of your maximum Life over the next 8 seconds.  Generates 3 Fury.

Triumph is the rune that really makes Frenzy worthwhile in larger-number combat, as it lets you drop some other defensive effects in favor of more damage- or just makes you as durable as all hell when mowing down tiny things.  This is a rune to avoid if you’re using Frenzy against a small number of large targets, though- you want the effect to go off frequently, since it doesn’t care what you just killed, only that you killed it.

Vanguard: Deal 110% weapon damage to one target.  Gain a 15% speed boost to Frenzy that stacks up to 5 times (maximum 75% speed boost).  While Frenzy is faster, you gain a 15% increase to your movement speed.  Generates 3 Fury.

Vanguard is very important for certain boss battles- things that charge like the Butcher, for instance- or if you’re fighting a small number of powerful things that are spread out.  Also if you just like troll-running your way across the battlefield.  Be aware that this rune isn’t going to please a lot of number-crunchers, since it doesn’t have a set numerical result- while the speed increase is a set number, being able to respond to the need to move is key to being able to use Vanguard, and if you’re bad at repositioning or just don’t like it, this rune is pretty much meaningless to you.

Smite: Deal 110% weapon damage to one target with a 20% chance of smashing them with a bolt of lightning that stuns them for 1.5 seconds.  Gain a 15% speed boost to Frenzy that stacks up to 5 times (maximum 75% speed boost).  Generates 3 Fury.

Smite turns Frenzy into a hybrid between itself and Clobber, with the interesting effect of stunning more frequently and therefore just generally being more awesome.  Which makes Clobber sad, but by the level you get it, an upgrade makes sense.

Maniac: Deal 110% weapon damage to one target.  Gain a 15% speed boost to Frenzy and a 4% damage boost to everything  that stacks up to 5 times (maximum 75% speed boost, 20% damage boost).  Generates 3 Fury.

Maniac is probably the ultimate in single-target destruction for Barbarians, turning Frenzy into a storm of death and weapon.  Or possibly deathweapon.  Its effect stacks onto the base Frenzy effect and really just makes it sweeter than ice cream.