Call of Duty WW2 Zombies: How to Get Bloodthirst Tesla Upgrade Variation - needed for "Dark Arts" trophy & achievement.

PREPARATION STEP (BUILD NORMAL TESLA + LIGHTNING ROD DEFENSE)

Before you attempt this, do the normal main easter egg. You must complete the main easter egg up until the Lightning Rod Defense.

Step 1 (Shoot Sparking Lamp):
At the Riverside area there is a flickering street lamp (near the starting area by the lake). You must shoot the flickering street lamp with the normal Tesla Gun.

Step 2 (Follow the Spark):
Now shoot it with any other gun that uses bullets. This will cause the spark in the street lamp to move on to the next street lamp. You must follow and shoot the spark. It will always be at lamps. It goes around the street lamps at Riverside, then to the starting area, to the bunker, to the morgue. The spark stops in the morgue. The problem is that not all lamps along the way have a spark and you have limited time to find and shoot the spark. It can also jump to lamps that are off, in which case it just looks like a green light. It's highly recommended you check out the video above for the path and memorize it. Now the good news is that you can try this as often as you want each round and the order/locations of the spark will always be the same as in the video above. The bad news is that you must shoot the starting lamp each time with the normal Tesla Gun and ammo is very limited. So if you mess up too often you'll have to wait for a max ammo to drop. Look at the video and do a practice run before shooting the lamp.

Step 3 (Get Battery):
When done correctly the Bloodraven Battery will fall from the ceiling in the morgue. Pick it up and insert it in the container in the morgue, near where it fell off.

Step 4 (Kill Pest Zombies using Morgue Trap):
To power up the battery you must kill big groups of Pest Zombies using the Morgue Trap (the one that causes spikes to come from the ground). Pest Waves happen every 5 rounds (round 10-15-20-25 and so on). Train all zombies of a pest wave, run with them in a circle through the morgue, and then activate the trap. Just run into the trap, it does very little damage to you and will instantly kill all Pest Zombies. You must kill 2 big groups of Pest Zombies using the trap to power up the battery!

Step 5 (Lightning Rod Easter Egg Step):
If you haven't already, complete the main easter egg up until the Lightning Rod Defense. Only after defending the Lightning Rods you can continue with the Tesla Upgrade.

Step 6 (Defend Battery):
Once the battery is powered up, pick it up and bring it upstairs (you'll know it's powered up because you can interact with it and pick it up). Insert it in the machine in the morgue that previously gave you a part for the normal tesla gun. Hold the interact-button to close the hatch. Now you must defend the battery for about a minute or so. Zombies will attack you and also attack the battery itself. There's a health-bar on the battery, the zombies aren't allowed to destroy it.

Bloodthirst Upgrade Complete:
After successfully defending the battery, pick up the part from the machine. Now you can return to the Tesla Upgrade Station in the Command Center (Bunker) to build the upgraded Bloodthirst Tesla Gun.