Sun Machine Reactor (SWTOR Decoration)

This special achievement decoration can only be earned by completing the “An End to the Exarchs” achievement, which is completed by killing each of the Exarchs at the end of each Heroic Star Fortress, for a total of 6 Exarchs.

If you defeat the Exarch at end of each heroic mode Star Fortress, you’ll get ten copies of the Sun Machine Reactor decoration.

Nar Shaddaa Exarch Lesin Tyn – There is one Exarch that’s harder than the others, and that’s Nar Shaddaa’s. This Exarch heals itself with a casted ability called Esne’s Avarice. If your DPS is too low, you’re going to struggle with doing enough DPS to cancel out him healing himself. Interrupting the cast sometimes works, while other times he’ll simply restart it, so you can start by interupting as many as you can. Beyond that, you’ll need to use the same tricks to get better as in any other content – raise your companion’s influence, learn to play your class better and use your abilities more efficiently, use a stim, get better gear, use heroic moment, or bring a friend.

Star Fortress Achievement Guide