From the preview:
Followers of the Dark Side know no limits in their quest for greed, ambition, and power. Those who would use the Force for dark gains will stop at nothing to accomplish their goals, and seek to dim the Spirit of Rebellion across the galaxy for their own selfish desires.
Today, we’re looking at the Blue Villains in Spirit of Rebellion, the newest booster set for Star Wars™: Destiny. These followers of the Force use the Darkside to pursue power at any cost, trading health and even their allies for powerful, consistent effects.