Even f2p have some rares and gold summons. Stuff like Sage Naruto/Iruka/Wb Asuma/Danzo/Ningendo can make massive difference. Luckily i saw your post for another exam so i remember you have WB Asuma and i am gonna use Iruka cause i hope you have him and if not, he should be in current event, get him lol.

WB Asuma *x Iruka
*x *x *x
Main *x Naruto

1
3
3
2
2 Talents with purple slug.

Turn 1 - Iruka and Fire main mystery on enemy Fire main, make sure you click Iruka first so Shurado try cancel him.

Turn 2 - Naruto on WB Asuma.

Turn 3 - Ignite to bait Shurado, WB Asuma on Sasori.

Turn 4 - Naruto on Shurado.

Turn 5+ - Finish Sasori, he is no threat alone, he is non prompt so if Naruto don't have 2 clones up, wait till he spawn then you can do bigger damage mystery.