Example for adding a new dungeon in D2R
Just cube a town portal scroll while in Harrogath and a red portal will open to the new area. The area is a copy of Act 5 pits, with a boss room, and then a final area with 5 super chests.
This could be easily extended to be as many levels / boss areas as you like. You will need WINDS1 Edit (https://www.d2rmodding.com/utilities) to modify the super uniques that spawn on the boss areas.
Bonesy and D2RModding.com Discord for the assistance