Batman's Batarangs

If you want to become the Dark Night, you'll first need to collect some materials. Most of Batman's Stuff can be crafted with a new ore called Stygian Iron. You can craft it into a wide array of Stygian tools and armour, and you can also craft Batarangs out of them with three ingots. Throw in some redstone and gunpowder and you can make it explode once it hits something. Nifty!

There's also a bunch of petrified trees around. They can be found in the wasteland that now generate above and below the surface. They look cool, but the trees are the best part. Not only are they really nice looking and rare (since you can't exactly plant one), but they are used to craft an item that's very good early on.
Combine your new Stygian Armour with black wool to get Batman's Suit. When you have the full set on, your gamer tag is hidden, concealing your identity.

With some wool and a bit of petrified wood, you can create the Bat Glider, an item that's very useful early game. Holding it slows your fall to a crawl, allowing you to cross gaps and float off of high ledges with no injury!

Use that Stygian Pickaxe you didn't make, along with some Stygian Iron and string, to craft the BAT HOOK! Go wherever you want, whenever you want, at no cost! Combine it with the Glider for extra movement capability!