If you want to craft the Tretaxe in Dolmen, you’re going to have to dig up two sets of Tretaxe Parts. Rather than farming these off enemies, you need to locate Drillers, who will gift you with the parts you need.
So I’m going to show you where you can find both sets of Tretaxe Parts in Dolmen, since both of them are located in secret areas of the game. Both of these, I should point out, are in the Wastelands in Act 2.
The first set of parts is located in the Vahani Excavations secret area, where you encounter the optional Dementula Insane boss. Once you defeat the Dementula Insane (or Corrupted Dementula), you’ll be able to go deeper into the caves here. If you haven’t yet beaten the boss, this area will not yet be open to you.
Here’s a video that shows the path:
Your starting point is the Ore Plant teleporter in the Wastelands. If you haven’t discovered this area yet, I’ve written a full guide for that, which you can check out here.
The second set of Tretaxe Parts is located in the Secret Grove secret area. Here’s a video of the exact location.
This time, the starting point is the Power Plant teleporter in the Wastelands.
Note that entering this area for the first time will earn you the Secret Grove Trophy/Achievement. Also, there’s another Driller here named Nicole, who will give you a Driller Flame Tank. You’ll need two of these in order to construct the Driller Pickaxe.
I should also point out that the first time you find a Driller, you’ll earn the First Degree Contact Trophy/Achievement. When you find five of them, you’ll earn Five to Remember, and if you find every hidden Driller, you’ll earn All Drillers.
And that’s how you find both sets of Tretaxe Parts in Dolmen!
