The Nether
The Nether is generally the 'second' dimension in vanilla. It's pretty bare and dull, but All Dem Dimensions adds a new dynamic to it: a use for the Nether Fortress.
Essentially, the nether fortress serves the same function as the Overworld Stronghold; to bring the player to the Boss Realm of that dimension. In addition, Blaze Rods can be found there, which is used to eventually craft Eyes of Nether through a series of other recipes. A potential concept for the recipe is an Ender Pearl, 4 Fire Charges and 4 Lava Cores (obtained from Magma Cubes in lieu of Magma Cream) (Credit to Jellomob for the the idea behind Lava Cores.) However, no recipes have been finalized yet.
Materials For Tools
Nether Root Wood / Nether Thorn Wood-The most basic tool type. It can be used to break basic blocks, such as planks, Netherrack, and Soulstone.
Soulstone-Stronger than wooden tools, it has the ability to mine tougher blocks such as Infernium ore.
Infernium-Even stronger than soulstone tools, infernium tools have more durability and the ability to mine ruby ore. It has a very low enchantability, but has a 25% chance to smelt item drops or light mobs on fire (fire doesn't affect nether mobs)
Undecided-The Nether's vanity tier has yet to be fully decided
Ruby-Ruby is the Nether's god tier, and has a fairly large amount of uses. It is very strong, and has the ability to smelt drops or light enemies on fire(even damaging nether mobs) 50% of the time, but is unable to be enchanted.
Making a Nether Portal
You will need to make an Obsidian Frame, and light the inside with a flint and steel.