Darkness Expansion
This addon adds creatures and items with the theme of darkness. All items that are not obtained in the crafting table are dropped from mobs. All mobs are born in the negative layers and on top of the deepslate block, so the player can easily build a mob trap with deepslate blocks and get several of these mobs.
Darkness Expansion
This addon also expands the difficulty of the game, but at a balanced level, since mobs are not found so easily.
Showcase video
Mobs
Darkened: Drop Darkened Flesh & Dark Heart
Dark Phantasm: Drop Dark Eye & Dark Essence
Darkened Flesh in furnace = Dark Essence
Items
Dark Eye: Shows all mobs in a radius of 20 blocks
Dark Heart: High Regeneration Level for 10 seconds
Darkness Staff: Shoots darkness projectile
Penumbra: A shadow that transforms into any tool. Use crouch and click to reset
Penumbra Magic: It does the same thing as the ordinary penumbra, with a single difference. It automatically enchants the transformed items with the best enchantments.
Images in game
I added more things in the post and important details.