For the Heretic Fortress level I constructed gameplay spaces out of individual wall, floor, and ceiling tiles. I then added scripted objects such as locked doors, enemy portals, and destructible walls.
Once the heroes reacha checkpoint they all channel on the altar to seal the way behind and opent he way forward. Any stragglers have a short time to catch up before they are teleported to catch up. The checkpoint system was set up to allow streaming the previous rooms out and the next rooms in.
Room and Door Logic Scripting
When the heroes enter a room the enemies start spawning and the entrance and exit are locked until the encounter is cleared.
Shadow Realms Demo Reel
I managed to cobbled together some highlights from IGN's coverage. Environment Art by Chris Hahn. Music courtesy of Ross Bugden:https://www.youtube.com/channel/UCQKGLOK2FqmVgVwYferltKQ