Although this build utilises the Band of Primal Power, It works OK without it, & this build can be used to unlock it.

Primary Attacks (attacks with your chosen weapon, for example Slayer's Blade) generate Energy (blue bar under the players health bar).
Power abilities will trigger when you have full Energy.
Energy is gained not on attack, but on enemy hit,
investing in the following stats will therefore increase the rate at which you generate Energy, & thereby how often you activate your power abilities:

• Attack Speed
  
• Instant Attack Chance

Focusing on Energy generation in this manner is crucial for this build to work properly.

Race: Human
Class: Barbarian
Origin: Veteran of the War
Weapon: Slayer's Blade

Class Masteries (roughly in order of importance):
Giant's Reach
Resilience
Primal Strength
Rampage
Bloodthirst

Power Abilities:
Primal Roar

Passive Ability:
Quick Strike

Artifact:
Zaladon's Ring of Rapid Strikes
Band of Primal Power

Movement Ability:
Leap