This is to obtain the Lightning variant of the protobuffer.

Obviously you need to get the base variant of the Protobuffer first to be able to upgrade it to this new variant.

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With your base Protobuffer, head to the South Upstairs area, where you will find a glowing box with "HZC TAU" written on it.

https://imgur.com/a/3oUaM4L

Shoot open the top of the crate with your Protobuffer to get an empty vial and start this upgrade quest.

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Now that you have started the quest, 4 electrical boxes in the map with "TAU" written on them will have their lights start blinking.

• One is in the North Gym, across the room from the teleporter.
  https://imgur.com/a/3eeeXMx
  
• One is in the North Entrance section, next to the other North teleporter on a pillar.
  https://imgur.com/a/FELbCtM
  
• One is in the South Entryway, very close to the Tau box that you got your vial from (just go down the stairs).
  https://imgur.com/a/jNsHWn7
  
• Final one is in the South Gym, in an upper area not accessible by players.
  https://imgur.com/a/43A6kPB

Each of these boxes will each blink a certain number of times before stopping briefly and then doing it again (Don't worry this is not time sensitive). What you have to do to complete this step, is to go to an electrical box, see how many times it blinks before it stops, and then interact that many times with the computer in the South Lower Hallways (room right next to Banana Colada).

https://imgur.com/a/Gb1Q8hg

If you did it correctly (the computer will tell you), the corresponding electrical box will start to glow. Go back to that electrical box and shoot it with your Protobuffer. This will release an orb on the ground which will create an electric circle. You have to kill about 6 zombies inside the circle with the Protobuffer to be done. The circle lasts only about 20 seconds but you can just shoot the electrical box again with no penalty.

If you did this correctly, the electrical box will be empty and a blue orb will appear near the fountain area. Do this process for all the electrical boxes (4 times in total) and all the orbs will start emitting lightning. Interact with the lightning to charge your vial. Wait a couple seconds for it to be done and pick your vial back up again.

https://imgur.com/a/5OBg2Wi

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A big blue light in the sky will appear to guide you to where you upgrade your Protobuffer.
If you can't find it, it's in the North Cafeteria.

https://imgur.com/a/tZB6uac

At the priming site, put your charged vial in the machine to prime it. You will then need to kill about 30 zombies around it. Once done, take out your Protobuffer for the last time to upgrade it to the Lightning Variant, the "HZC-5G Protobuffer Tau".
Congrats you did it! \(￣︶￣*\))

https://imgur.com/a/RmcqxxD

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https://imgur.com/a/cammBdv