In this video guide I will show you how to craft a weapon using material from a defeated world boss then upgrade it to level five. Now typically the first run on a campaign roll world boss will be Singe. Who looks like a tree root dragon. If you want to know more about him I also have a video here.
Once you defeat Singe
you will get a Blazing Heart
in your inventory items under the materials tab. Once you get that head back to Ward 13 and talk to the sassy mod lady
. You will then be able to craft it from her.
After that head to the merchant guy
who sells the guns and upgrades them. Simply upgrade it as far as you can. Now chances are you did this right away and can't get it all the way. You will need plenty of iron, lumenite crystals, and forged iron
. Forged iron will be dropped later on by the enemies so don't worry there. Once you get enough of it you will be able to upgrade it to level five for the achievement.
Just on a side note there will be plenty of other world bosses
who drop the items to craft more in case your campaign is different. As well as some mini bosses as well. Which should count since the game is glitchy enough. If not let me know and I will remove this little add-on.