The Hunting Dimension is an always night world to make mob farming and hunting easier to do at any time of day. Portals are crafted the same as Nether Portals and ignited the same way or with any other fire spark.

You have to sneak to enter the portal and once in, be ready for enemies all over.

From there you can find most any mob you may need to farm and you can set up grinders that have higher chances for drops and additional XP.

And this mod also adds the ability to change biomes of the Hunting Dimension using creeping moss. The biome can be set with different types of saplings and simply right-clicking with it in hand to change the biome instantly.

This mod requires an additional API found here.