Help beating lvl 4 shadowmonster

[StraferHighwind]

I've been stuck at the lvl 4 shadow monster for months! It's just too strong for me to beat. I was around lvl 28 when I made it to him in stage 4 and. Now lvl 39 and still can't beat him


I've tried every arrangement of strafer, Sakura, Sarah, Raina, and Christina. When I use Sarah I never get to use her bc the shadow monster always goes first and kills her instantly before I get a chance to do anything.

All my heros are MAXED on blessings and skills both offense and defense. They all have at least three soul stones from game lvl.

I'm honestly ready to quit the game if I can't beat this lvl in the next few days. I've had enough of this BS!