The primary job of a group barbarian is to keep the life, mana, skills, and defense of the group enhanced. Any damage the group barb does to the monsters is a pure bonus. Fortunately with the added effect of mercs, spirits, and Fanaticism aura this barb will do some very significant damage.
Shout is maxed. This will increase the defense of the group.
Battle Order is maxed. This will increase the life and mana of the group.
Battle Command has 1 point in it. This is all that is required. That one single point will increase every skill in the group by one. Think about this it is as if every member in the party were carrying three skillers. One skiller for each tab. So this one simple yell by the barb as the effect of 24 skillers. Care to guess how much a skiller costs? Well multiple by 24 to get an idea of how potent this skill an be. All from one single point.
Please note the 1 point in War Cry. War Cry is useful for its stun effect. You will not be able to kill with it, however, you can hold Lister's buddies (not Lister himself) still while a traps assassin or sorc kills them.
On this tab we point one point into each of the lower skills, and one point into each of the top three masteries. These are one point wonders. A single point with the bonuses from equipment will grant a huge benefit.
The group barb uses Frenzy as its weapon skill of choice. This skill is powerful and fun. As a barb successfully hits monsters it will speed up -- hitting and running faster. A frenzy barb can run faster than a sorc can tele. Combine that with Leap Attack and you have a barb that can really move.