[Arknights] DV-EX-1 CM - Low-End Squad (w/ Ling) 

Basically promote any operator E2 and take Ling as a Support Unit (if you don't have her). The stage is clearable without her, but I'm lazy.
If some ennemies leak, take additional melee operators to block.
Squad used :
Myrtle, E2 Lv.15, S1M3, P6 (doesn't need the Mastery 3)
Fang, E1 Lv.35, Skill Rank 7, P6
(Support Unit) Ling, E2 Lv.90, S3M3, P3, Module Lv.3 (Lv.2 module increases the max number of summons deployed simultaneously to 4)