4Game

I expect someone, probably not me, could kill the last boss first a lot sooner than most folks think possible. The most difficult (not tedious) challenge would be finding the boss' location, but it could theoretically be done with only a stone ax and hammer.

Here's the solution:

1. Build a raft to cross water and search for the final boss' location.
2. Once you find the boss' location, find a mountain biome on the same landmass (this might not be possible on all maps)
3. Build a wolf trap to capture, tame, and breed 2-star wolves. 1-star wolves will do in a pinch. You'll need about 40, 2-star wolves or 60, 1-star wolves.
4. Sneak around the planes and collect the totems.
5. Bring the wolves to the altar and start the final fight. The fight should be over before Yagluth can finish rising out of the ground.

While this method would avoid mining bronze, iron, and silver, there's still some tedious work involved here. Yet, I expect someone who expertly knows the planes biome, how to tame and breed wolves, and is good at corpse running, could use this approach to defeat Yagluth relatively quickly without an ounce of cheese.