How enter endgame?

Hi.

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I finished the campaign and first dlc, not sure what should do to aproach endgame... Should y repeat adventure mode of.... What, 3 dlc first then repeat? Wich dificulty level?

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The game doesnt explain this very well, and threads here seem outdated. I am now only running passages and killing trash mobs, what is so boring... But i wanna give the game a apportunity.