This is from the dev post April 14th
Greetings,
Here is the information on the new event that will be going live today with the Balance Update.
Ability Material Omega Event: This special limited time event will reward players with Ability Materials of all levels, including the elusive Omega Material! In addition players who defeat the lowest level of the event will be awarded a large number of Credits. Here are some additional details on the event:
Each day of the event will only require 3 characters from a predetermined list
Ability Material Omega is only available at Level 80 outside of this special event
The new event will allow players to earn enough Omegas over a 12-day period to level up a single character's abilities
Each event will have 3 levels of difficulty
Easy - Unlocks at Level 30
Medium - Unlocks at Level 50
Hard - Unlocks at Level 70
Unless you had characters over 70, you were unable to obtain actual omega pieces. Those were only found in the hard node.