Just to take that "unit" slightly further.
Put cassius, lysander, and a few stern guard in a drop pod.
1st turn cassius has llittle effect, but lysander gives rerolls on all shooting which will hurt something a lot!
2nd turn you have a T6 Lysander. This solves the instant death dilemma, gives you lots of 2+/3++ and 3+/4+(FnP)
This unit will run you probably somewhere in the region of 600 pts, but it will almost certainly take an objective for you, or crush part of an enemy line (which is brilliant in
HQ missions).