This fellow uses, I believe, the greathammer weapon from Complete Warrior. It has no special rules beyond its damage die, x4 crit chance, and status as an exotic weapon, so you should not need the book to use it.

"Awesome Blow" can be found in the MM. Improved Bull Rush is designed to capitalize on the creature's enormous strength. It will be most useful if the ogre barbarian is accompanied by other ogres, who can make attacks of opportunity on the bull rush victim, who will be hurled about the map by the Bull Rush and the Awesome Blow.

Note the creature's Power Attack and his two-handed weapon. For every 1 point reduction in attack chance, he gets +2 damage. If he rages and takes -3 on his attack roll, he can still make a +9 attack to inflict 3d6+19 damage, for an average of 30 hp. Your players don't want to get hit by that.

As with all ogres, if they can take out the light source they will enjoy a tactical advantage. They should avoid dwarves, who get combat bonuses against them.

Ogre Barbarian CR 4Edit

Male ogre barbarian 1
CE Large giant
Init +0; Senses darkvision 60 ft, low-light vision; Listen +3, Spot +3
Languages Giant

AC 19 (+5 natural, +5 armor, -1 size), touch 9, flat-footed 19
hp 44 (5 HD)
Fort +10, Ref +1, Will +2

Spd 40 ft (in breastplate)
Melee +10 greathammer (3d6+10/x4)
Space 10 ft; Reach 10 ft
Base Atk +4; Grp +15
Atk Options Awesome Blow, Improved Bull Rush, Power Attack
Special Atk rage 1/day
Combat Gear potion of remove fear

Str 25, Dex 11, Con 18, Int 6, Wis 12, Cha 4
Feats Awesome Blow, Exotic Weapon Proficiency (greathammer), Improved Bull Rush, Power Attack
Skills Climb +7, Listen +3, Spot +3, Survival +3
Possessions combat gear, large greathammer, large breastplate

Rage: The ogre barbarian can rage once a day for 9 rounds, at the end of which time he is fatigued. While raging he has the following stats:

AC 17, touch 7, flat-footed 17
hp 54
Melee +12 greathammer (3d6+13/x4)
Fort +12, Will +4
Str 29, Con 22
Climb +9