Palpatine
Palpatine is one of the most unique heroes in the game as he can fire lighting as his primary weapon which is pretty cool. He has a decent amount of health and a lot of health regeneration with a lot of mobility. His forward dodge covers more distance than a regular one and he can use force jump to get to greater heights. One of is drawbacks is that his primary lighting attack doesn't do a lot of damage, so against other heroes or high health enemies he can have problems but that's where his abilities come in useful. I would also recommend getting the increased stamina start card as he runs out of stamina pretty quickly. You can also use the other trigger to use two handed lighting which does more damage but takes up more stamina. So I would recommend using mainly two handed lightning by holding down both triggers (aim and fire) to deal extra damage and use his force jump to evade shots while regaining stamina. His dark aura ability is really helpful as it can damage enemies through walls and slows them down which allows palpatine to kill multiple enemies with ease. You can use this against loads of grouped up enemies followed by a chain lightning to get quite a nice multikill. His stun ability allows him to shock the ground in front of you stunning enemies. This is useful but only on retreating enemies and grouped up heroes while with your team as it eaves you vulnerable to damage. It works well in a 1v1 against a saber hero but against a group of soldiers, you will take some damage. His chain lightning ability sends out a bolt of lighting which chains from enemy to enemy doing damage. This is probably is most efficient killer because its fast and decent damage. In galactic assault if you fire this into a group of enemies you can finish them of with dark aura and lightning. One thing to remember is that he can't block so stay mobile with dodges and jumps.