There are three stone dragon statues in the Der Eisendrache map that you need to find and activate for a wonder weapon. That is how you will get the Wrath of the Ancients, a powerful bow that comes with a charged attack for insane damage.
Compared to most other wonder weapon quests, this one is pretty easy to complete. You can get it down within the first five or seven waves. You only need to feed the three dragon heads by killing zombies nearby which is what you will be doing anyway. You just need to know where the dragons are located.
Dragon #1
Make your way to the Castle Courtyard to find the first dragon statue in Der Eisendrache. Starting from the spawn point, head through the door on your right and then keep going straight to reach the courtyard. The dragon can be found below a staircase in the far western corner of the courtyard. Kill a zombie nearby to revive it.
Dragon #2
From the first dragon head location, make your way below the castle to reach the Research Lab. Take the stairs next to the Death Ray Trap and Teleporter Machine to find the next stone dragon in BO3 Zombies.
Dragon #3
For the third and final stone dragon in Der Eisendrache, exit the lab and make your way to Undercroft. Exiting the lab and heading straight will head you to a Perk-a-Cola machine. There is a tunnel right next to it. Use it to go down and you’ll find yourself in front of the third dragon.
How to get the Wrath of the Ancients bow in Der Eisendrache
You do not need to craft the Wrath of the Ancients bow in Der Eisendrache. After feeding all three stone dragons, head to the Knight’s Tomb which lies above the location of the third dragon.
This is the room with the tinted windows. You will find the bow floating above a crate at the end of the room. Just go ahead and pick it up.