Blade and soul gold is a very vital resource in this game. You require it for a lot of diverse aspects of the game, among which the most important aspect is upgrading your warheads and accessories. For upgrading you have to craft, get hold of, or pay for various materials. Nobody is capable of crafting each and every material that they require and thus all players must pay money for a number of them. https://www.youtube.com/watch?v=i5TK2nSzGyQ