In order for Jak to control his magic in Immortals of Aveum, he will need special equipment and gear. You get default equipment for wielding your red, blue, and green magic, but you're not stuck with the basics for the entire game. During the opening chapters, you will no doubt have collected some gold and essence, but not known what they do or how to use them. These are for upgrades and crafting, which is how you will keep up with the challenges of the Everwar.
How to upgrade and craft gear
While you are never told why you should, instinct alone will probably have you scooping up as much gold and essence as you can during the first three chapters of the game. That's good, because once you hit chapter 4, you can finally spend those materials to improve your equipment.
Step 1: Play the opening three chapters and collect as much gold and essence as possible.
Step 2: At the beginning of chapter 4, after speaking to the captain, look to the right of the gate to see the Forge.
Step 3: Interact with it to get a quick tutorial on how it works.
Step 4: Every item will cost gold and some amount of colored essence to craft. If you don't have enough, you can also dismantle old gear to recover some materials that way.
In the Forge, you are able to either craft brand-new pieces of equipment for each sigil, ring, and more, or upgrade the ones you currently have to increase damage and other stats. This isn't the only Forge in the game, and you can usually find them in all the hub areas. Simply look for the symbol of a Hammer on your map to locate one.