So I'm a level 52 and my main team right now is a Sith core of Vader lead with Sidious Dooku, along with 2 tanks in Chewie and Royal Guard (basically placeholders for future replacements). The team works, but I notice that Dooku and Vader keep getting worn down with no way of healing up, particularly in Galactic War. There's 50 Darth Nihilus shards in my crystal shop right now. How good is Nihilus and how well would he synergize with my 3 Sith? If I'm not mistaken, slotting Nihilus in at leader should theoretically instantly fix my sustain issues. The only reason why I haven't done it yet is the slight negative synergy with Sidious.