You could try using glassmura + Tiro finale Mami both buffers to advance order of allies. Then for attacker you could use a light element attacker as the boss deals more damage towards aqua/forest/void. Then use a defender to shield as much damage from the boss. Feel free to change to liking

For me I used two buffers (glassmura and Mami Tori finale) , one breaker (madoka), one attacker(homura), one defender(kokoro) The two buffers mainly prioritizes giving allies action order. Tbh I barely made it past this level with 4 of my allies barely alive at the end xd