For Skeletal Avenger achievement hunters , this guide is going to show you how to get the Headway achievement, which is by not using your primary weapon ( Whatever you have in your hand/s ) once.
Words before the Guide starts
This is from personal experience, so it may not be the best way to get this.
It also is heavily RNG dependent to get the Kobold Boss. [Unsure about this one.]
Items and upgrades you may need:
Upgrades: Health, and Skull damage. If you already have armor at this point, you may already have decent stats.
Items: Mortar Hat, and anything else you can get your hands on.
How to survive a quest without using Primary fire
If you find or have already found the dash trinket, use it.
Find a level 1 quest and start dashing away to the exit and only using your Skull as your weapon, I recommending binding Primary fire to another key just incase you accidentally tap it. Although I recommend just ignoring most enemies except for the mages, or just out run the mage if your decent at dodging.
How to defeat the Kobold Boss with only the Skull
Keep spamming the Skull on the boss, if you have the free thinker perk, then just keep your distance while dashing away.
If not, then bomb, dash to get your head and dash out again. Do this for several minutes and you should kill the boss in no time. Make sure you do this in a open space since its really easy to get stuck in a corner.
You may also get the Rampage achievement if you ignore most of the enemies and kill 10 rats in less than 10 seconds.