Last night my players had a choice of going to the Shadowfell or going to the Feywild. I prepped the Feywild. They went to the Shadowfell. So I had to put together something on the spot essentially (the results of which will be up later this week made into a full paragon encounter).
I wanted to use Fantastic Terrain to make the encounter different, but the Fantastic Terrain isn’t in any of the digital tools and is scattered over many books making it nigh impossible to do quickly. But here @KatoKatonian came to the rescue with his awesome reference list.
Go check out the (Mostly) Comprehensive List of Fantastic Terrain he has created here.