A squishy ballgroup member in noCP according to my calculations in this thread:
https://forums.elderscrollsonline.com/en/discussion/487313/solution-to-ballgroups-zerggroups-and-even-lag-caused-by-faction-stacking/p1
requires you to do at least 146 666,(6) damage in a single second to instantly die. That is the number that you would see on your tooltip.
Such burst damage is impossible for one person... or is it?

Assuming that you could hit all 24 members of a ballgroup with a single Proximity Detonation and at least some of them with your Stalking Blastbones, Avid Boneyard synergy and Glacial Colossus, it is possible to do around 128k damage. Not enough even for a squishy ballgroup member... but not necessarily if at least one of your targets gets critical hits from at least a few of those abilities. And should you kill at least one of them, then the Vicious Death Proc should be able to either kill a few more or at least counter their healing enough so that other players might be able to overwhelm the ballgroup.

This build also works against zerg groups.

However before you decide to run it, there are multiple drawbacks of this build:

1. It is very, very squishy. How squishy exactly? Almost like a zergling in pve build.
2. It has laughable magicka recovery.
3. It requires you to buy expensive golden jewelery from Vicious Death set or craft at least purple jewelery from Clever Alchemist set.
4. You will probably die while trying to kill the ballgroup.
5. The combo is very hard to execute perfectly and you have to do it perfectly.
6. It is viable only against a squishy ballgroup members (70% damage resistance, 29k max health). Killing tanky ballgroup membvers would need perfect coordination from 3 people running this build.

Here is the build:

• Balorgh (2x light)
• Clever Alchemist (1 heavy, 1 medium, 3 light)
• Vicious Death (3 jewelery and lightning staff)
• Ice Staff of Willpower
• All body pieces are in Divines with Max magicka enchantments.
• Lightning staff of Vicious Death is in Nirnhoned (Sharpened might be slightly better for damage but Nirnhoned will make you slightly more survivable thanks to increasing your self healing.
• All jewelery is in Arcane trait with Spell Damage enchantments. Infused trait will give you slightly more damage but less magicka will greatly decrease your defensive capabilities.
• Food: Max Magicka
• Mundus stone: Apprentice

Front Bar:

1. Stalking Blastbones
2. Avid Boneyard
3. Resistant Flesh
4. Structured Entropy
5. Inner Light
6. Glacial Colossus

Back Bar:

1. Proximity Detonation
2. Intensive Mender
3. Elusive Mist
4. Beckoning Armor
5. Necrotic Potency
6. Ravenous Goliath

How does it work?
First you cast Proximity Detonation and use your potion. You have to align its detonation with Stalking Blastbones hit, Avid Boneyard synergy activation and Glacial Colossus. This means that you have to predict where the ballgroup will be, hit it with not one but two aoe abilities and actually enter the ballgroup. Elusive Mist might help you with surviving entering the ballgroup and make you stealthy enough to avoid their sight. If you do everything perfectly and other players will chip in, you might actually wipe the ballgroup or at least cripple it enough to overwhelm survivors.

Honestly I'm not satisfied enough with this build. And it is all theoreticall at this point.
I'm already thinking about alternatives.