I like the leadership of EP for the Empire and Sith. But with the power creep making it irrelevant, the zeta will need to include special abilities for Vader and Royal Guard.
It could tack on this. Zeta leadership
Darth Vader leadership is fully active as long as Emperor is alive. The Royal Guard receives an additional 50 % Health and Protection. And Whenever the Emperor takes Damage Royal Guard taunts for 1 until damaged and Darth Vader has 100%counter. These abilities cannot be blocked.
Now the emperor is going to contend with rebels.
Crackling doom zeta
The special damage can now kill. And whenever cracking doom is active at the end of the Emperors turn, the emperor and random Sith ally get foresight for 1 turn.