I tend to save furnaces and such for Lando and Han since they have arena relevance.
Swapping a potency cross mod onto Cad helps out with the stun which can be really helpful.
I'm in the same boat though. Raid Han at the end of the tier 3 battle is a real PIA. Make sure Cad's stun is refreshed when you go into that battle. I try to save it for a few turns in after Han's gone Crit chance up.
I've come within one shot of a three star and then not even beat it the next go round. Figure the RNG has to roll in my favor soon.
