You can just start with veteran mode or master mode operations. (dulfy.net)
You can still run all nightmare mode operations (sorry, forgot... master mode nonsense) with existing gear. (dulfy.net)
So if you're a budding Game Master, D&D fan or just simply enjoy watching Critical Role to get an insight into the dangerously addictive D&D world, the Game Master mode in Divinity: Original Sin 2 could be a fantastic and relatively inexpensive way to experience it all first hand. (gamewatcher.com)