New content

Inverse Blocks is a mod that adds something called Inverse Matter:

Transmutation of items(ex. transmuting Rotten Flesh into Leather)
New items (ex. Amulets with special powers)
New blocks (ex. Charging Pedestal, Mob Grinder)
New crafting mechanic - Infusion
New tools (ex. Inverted Diamond Pickaxe)

A quick description of the new items and blocks

There are currently four amulets:

The Fire Amulet - Instantly extinguishes you when on fire
The Flight Amulet - Allows you to fly
The Saturation Amulet - Instantly feeds you
The Speed Amulet - Gives you a slight speed boost when sprinting

Amulets require being charged in the Charging Pedestal.

The Infusion Pedestal must be used to craft some materials and/or tools. It can be also used for transmutation of some vanilla items into there inverses(Rotten Flesh -> Leather, Grass -> Mycelium, ...).

The mod also adds powerful tools like the Inverted Diamond Pickaxe that can mine blocks in a 3x3 area. It can be made via Infusion crafting and the Inverted Diamond Axe which will auto-smelt any smeltable harvestable block.

You can find more information on the pages tab.

You can use this mod in your modpack.

The mod has an in-game guide, but I recommend using JEI with this mod.

This mod is still in development.