Idle Online Universe RPG

My monsters have level 28 and i can't level up more (enemies give me 0 exp) but i can't beat the lava boss, it just kills me in 3-4 turns, tried 3 different builds and different strategies, can someone help? thanks!

Try to use Bend time skill to freeze boss
make sure your monsters hove enough agi to hit first

Only use agi and main stat, about 30-40 more main.