Finish the Epic for the first time:

After a fleet has completed an epic, each member will receive a galaxy map for the epic's planet or the DFR blueprint for a special DFR. In addition, members will receive gold coins according to the percentage of their contributions to the fleet! (The amount of coins will range from 5,000,000 - 40,000,000, and differs from epic to epic.)

Finish the Epic for the second or more times (Epics can be completed more than once!):

If you complete an epic a second time, in addition to the gold coins you will also receive 50 - 400 energy cubes instead of the galaxy map!

Note: Fleet members who contribute 0% to the fleet will not receive any gold coins or energy cubes, however the member will still receive a galaxy map the first time the epic is completed.