GreedFall

This achievement is earned after you unlock all Magic skills and their respective upgrades. If you start the game as a Mage then Divine Magic Ring and Stasis will be unlocked automatically for you. This achievement should take a total of 25 skill points. Skill Altars will speed this up significantly. Remember that skills require at least 2 skill points to unlock, the ultimate skill will require 3 skill points to unlock so make sure to save some up. Upgrades for each skill only require a single point each. Here is everything you need to have unlocked to earn this achievement:

Divine Magic Ring (Unlocked automatically when starting as a Mage)
-Ravenous Shadows (1 Skill Point)
-Shadow Dancing (1 Skill Point)
-Destabilising Impact (1 Skill Point)
-Light Projectiles (1 Skill Point)

Lightning Dash (2 Skill Points)
-Faster Than Lightning (1 Skill Point)
-Light Shadow Impact (1 Skill Point)
-Ranged Shadow Impact (1 Skill Point)
-Whirlwind of Shadows (1 Skill Point)

Stasis (Unlocked automatically when starting as a Mage)
-Stagnation (1 Skill Point)
-Corrosive Emanation (1 Skill Point)
-Perfect Incantation (1 Skill Point)
-Crystallisation (1 Skill Point)

Shield of the Enlightened (2 Skill Points)
-Steadfast Light (1 Skill Point)
-Shield of Fury (1 Skill Point)
-Holy Bulwark (1 Skill Point)
-Blessing of the Enlightened (1 Skill Point)

Storm (3 Skill Points)
-Vulnerability Storm (1 Skill Point)
-Extended Storm (1 Skill Point)

Once you've unlocked all Magic skills and pop your achievement, that means you have enough Skill Points to unlock all of the Technical and Warrior skills too. All you have to do is save your game, then use a Memory Crystal to reset your skill points. Make sure to select your starting class as Warrior or Technical to save some skill points by starting out with their respective skills unlocked. This will be the quickest way to easily obtain both: