Impossible to beat levels

I know that in every game they place a mission that seems impossible.. Like a ceiling type missions

my suggestion would be to keep upgrading your heroes and get more speed so u can strike first and give urself a chance to heal.. Also, use heroes who can Ability Block

i have done all LS missions and hard missions..waiting for level 7 to unlock

as for DS hard mission, I'm stuck at 6B.. The last wave is currently impossible for me.. Level 66 with grade 8 gears.. With Ewok Elder as boss.. 

Also, u can directly ask on forums who can give u a specific ally hero for that mission

and FYI, DS level 5 mission, I think the second to last mission, is quite nasty with waves after waves of Jawas and all spams AoE skills.. Can only still 1* those dang Utinis