Mod generate irregular labyrinth inspired by Diablo (first one) created from various pre-defined 16x16x16 structures. Labyrinth started from Y=0 and below and continued to world borders.
Loot in dungeon generated by loot tables. They can be edited. How to edit them:
This mod need Cubic chunks mod for work. Cubic chunks itself is WIP mod and have no release versions yet.
Link to Cubic chunks thread:
MinecraftForge 1.12.2 and CubicChunks 0.0.859: