Go to the Lost Cave and use one Dynamite to blow open the entrance to the cave. Use a Fanon:Pick-Axe to harvest the crystals on the bottom of the cave. Next, go the Wood R Us to buy a Silver Axe. Then, go to the Fanon:Rocky Hillside to harvest one Rock Tree and turn it into a plank. (Note: Any size plank will work. Just don't go too crazy and make the largest plank you've ever seen. This next part will tell you why.) Then, go to the Den in the Taiga and send the materials though the hatch next to the Red Eagle Mark on the wall.
Next, place the Fanon: Crystal on Zolarketh's plate, the Silver Axe on Rukiryo's plate, and the Fanon:Rock Wood on Gusmanak's plate. The Crystal Axe will fall from the hole in the ceiling, just like the Rukiryaxe and play the same music.
On Fanon:Gem Wood, the damage is 2.0 per swing, with a cooldown of 0.4 seconds, close to the stats of the Rukiryaxe. On Fanon: Rock Wood, the damage is 1.5 per swing, with a cooldown of 0.55 seconds. On other variant wood, the damage is 1.4 per swing with a cooldown of 0.6 seconds.