Hazelia

As of right now JEI or any other recipe mod will be your best friend until I write up a wiki :)

Info:

The boss can be found in the Domanian biome underground, somewhere between Y= -55 / 0. To summon the boss you will need to right click the altar with the "Heart Of Hazath" which can be crafted, but will be consumed on use. All of the other crafting recipes such as the weapons should be in the recipe book, and will unlock once you get the main ore/resource for each item.