How Does the Creation Catalyst Work? Everything You Need to Know

wowhead.com:

The Creation Catalyst opens with the next weekly reset in every region. To celebrate its opening, we will answer the most asked questions about this new system and what can you do with it. Creation Catalyst Guide

The Creation Catalyst is a new system for Patch 9.2. This system allows you to transform Season 3 pieces of gear into set pieces for your class.

The Creation Catalyst is located all the way south in Zereth Mortis, high up in the air within the Catalyst Gardens. You first come across the Creation Catalyst during Chapter 4 of the 9.2 Campaign, Forging a New Path. The Catalyst is located high up in the air. You can either fly to the Catalyst if you have access to flying in Zereth Mortis, or if you can't fly, you can use a small teleporter located in the middle of the pool under the Creation Catalyst building to get there.

Can't fly? You can use the teleporter in the waters below the Catalyst to get up.

The Creation Catalyst is unlocked for everyone at the same time, there are no quest requisites to use it. Same goes for its teleporter.

To craft tier pieces with the Creation Catalyst, you must first obtain eligible Season 3 gear in one of the five tier slots (Head, Shoulders, Chest, Hands, or Legs) and then use the Creation Catalyst to transform this piece of gear into a tier piece.

Depending on which piece you're upgrading with the Catalyst, it will have a different Cosmic Flux cost.