Yes I have completed Challenge T2, because Challenge T3 is unlocked. That aside as its been a massive outlay relic-ing my rebel squad to complete it, I am more than aware of my previous hard won tribulations. My squad has managed to complete it at least the last 2 to 3 previous times. Not this time though.
The issue is not one of tactics, the issue is that Challenge T2 has suddenly become much harder. Other's in my guild have reported the same issue.
Its now impossible for me to complete, despite having a much stronger squad.
It could just be RNG. Yesterday I beat challenge III on the first try, today it took me three tries to get past wave 4 without losing anyone, then I 3* it.
Challenge tier II, however, I put on auto and the AI had no problems.
Looking at the profile associated with the ally code you provided--what team are you using? I find it hard to believe you could beat challenge tier II without C-3PO.
At any rate, try changing R2's triangle and cross for primaries that can actually be shared by Number Crunch, such as health, offense, or protection. Before my 3PAC was 7*, I found that R2 having a lot of protection especially helped him survive Challenge Tier II.
I would change Han's cross for offense primary. There's no real reason he needs potency--really, anyone with Chewbacca there, as Chewbacca gives Tenacity Down on his basic. I would try to find 6* offense primaries as well, for both the cross and square, and maybe the arrow if you think you can spare the speed. I also personally put a speed set on CLS so he can give the whole team tm more quickly.
