The Aspect of Efficiency is a Resource Aspect. It can be imprinted on Rings. It can only be used by Sorcerers.
Effect
Casting a Basic Skill reduces the Mana cost of your next Core or Mastery Skill by [35 - 50]%.
How to get Aspect of Efficiency
The Aspect of Efficiency can be unlocked in your Codex from
Domhainne Tunnels
The fastest way to get the Aspect of Efficiency is to gamble Rings on a Sorcerer.
The best way to get Aspects is to gamble your
Murmuring Obols