This should be a helpful build for unlocking the 'Edge of Darkness' Artifact, which is a useful item for many other builds.

Primary Attacks (attacks with your chosen weapon, for example Soldiers Sword, Scimitar, etc.) 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
  
• Projectile Amount
  
• Projectile Split Chance
  
• Projectile Pierce
  
• Double Shot Chance

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

Race: Human
Class: Thief
Origin: Stargazer
Weapon: Dual Blades (Soldiers Sword x2 or Scimitar x2)

Class Masteries (roughly in order of importance):
Incapacitate
Alacrity
Acrobatics

Power Ability:
Frostfall

Passive Ability:
Freezing Vortex

Artifacts:
Zaladon's Ring of Rapid Strikes
Frostmoon Pendant

Movement Ability:
Teleport