My suggestions against zeta savage:
- keep your nihilus alive until you can Anihilate him.
- Super stack his HoTs, use Boba’s special to super hit all his stacks (maybe add Phasma for guaranteed advantage crit).
- Nightsister plague drain him.
If you have none of these, I suggest using garbage toons as sacrifices to use up his cooldowns before going in with your best remaining characters. Sometimes I sack one toon at a time to reset the RNG. This was pre-GW rework though.