The mod I have in mind would first create a plain wooden mask using wooden planks in a crafting table. You can color it and wear it. The next part would be turning it into Loki's Mask. That requires a recipe including the wooden mask(of any color), Blocks of Emerald, and Nether Stars. It's expensive, but the product is pretty over powered. When you put it on, you get an increase in speed and jumping ability. Your tolarence for pain is much higher, and can be increased by creating The Mask's famous yellow outfit, which is made by surrounding yellow dyed leather armor in Emeralds making you virtually invincible. This armor can only be created while wearing the mask. While wearing it, you can also create two other items, a huge mallet, and a horn. The mallet works as a sword that is more powerfull than diamond. The horn, when you right click, emits the noise it does in the movie, and repels mobs 2-3 blocks back. I hope this isn't too much.
