
I had always wanted to make my own scenario but I had never really had the push to get it started. I had read about other people taking their D&D characters into the House on the Hill. They did a great job and you can read about it here. I wanted to take it the other way, instead of playing Betrayal with D&D Characters I wanted to play D&D in the haunted house of Betrayal.
I started by thinking of a scenario that would take all my characters there at the same time. You can just drop the characters in the Mansion, but I had another thought in mind. 2 of the players characters had just finished a campaign and were teleporting back to Waterdeep, and for my buddies character who was still in my family campaign I used his connection to his deity.
Bringing the characters together:
I decided that the characters teleportations would get interfered with, and they would all end up together in a summoning circle surrounded by cultists. I wanted the players to face an immediate threat, something easy that lets the players get into the scenario, lets the characters have a fight together that they can bond over. I find combat a great way to bring a group of strangers together.
Bringing Betrayal into the game:
The summoning room was the Pentagram chamber. I built the house before the game using the room tiles from betrayal, and as the players moved from room to room they flipped the tile and discovers what room was next.

While no event cards or omens were used, having the tiles as a mini map as well as taking influence from the different haunts in Betrayal, (how many haunts had traitors trying to summon some evil into the world in this house) It made for a fun experience for my players.
I loved the experiment of using Betrayal in D&D and it gave me the opportunity to make my own encounter. You can find both games at your local game store or Betrayal at House on the Hill here, and the D&D Players handbook here and basic rules here.
I really hope you try this out!