Clan boss: Ultra-Nightmare help needed

hey folks, how can I make my team do more damage? I want to reach 1 key threshold.

Every champ has warmaster mastery

https://preview.redd.it/u3q3j2ql5xof1.png?width=1315&format=png&auto=webp&s=64d2b572de900b183d05fe53c49bf82335894027