I, like most of you here I'm sure, struggled with this event for hours on end!
My line-up is as follows: G12 Bossk, G12 Cad Bane, G12 Greedo, G11 Boba, and G11 IG-88.
It's pretty well-known at this point that Dengar makes it waaay easier.
Anyways, to the point- I couldn't be bothered to grind up Dengar and wait for the next event, so I toiled away trying different strategies until I got it.
So here's how I did it:
1: Cad Bane got stunned, no ability block on anyone else. R-2 stealthed everyone except himself.
2: Greedo stuns R2, then Bossk bursts him down with the net.
3: Once R2 was down, I didn't have to worry about who to target. Boba uses Execute on chewie and he goes next.
4: I had to try and keep Lando either ability blocked or stunned while I killed ROLO to do away with all her stupid TM and ability block business.
5: Once ROLO was done for I could deal with Lando, and then finally Han.
-Boba's BH Resolve was what won it for me. Luck had it that they managed to get him low and then only kill him right after I had gotten another kill, allowing him to come back.
-While most strategies suggest bursting down chewie first and only succeeding if R2 didn't stealth right away, I simply couldn't get lucky enough between greedo's hits not proc'ing and either Bossk or Cad being stunned/ ability blocked.
-I used Bossk's frenzy to get as many attacks off as possible on the Contract target, which let me complete my contract shortly after Chewie died while attacking ROLO. The extra speed from the contract payout saved me from getting burst down by Lando's special and Han's ridiculous attacks.
-Boba has to use his ability block after chewie dies. This keeps Han from stunning our squad and bursting them down with Lando.
I wasn't able to do it until everyone actually survived the initial 2 turns. IG-88 did die after he took his 3rd turn, and Bossk after that, but once R2 and Chewie died, Bossk and IG-88's last couple hits on ROLO were ABSOLUTELY necessary to finish the contract and kill ROLO.