The Arena skill

The skill from our reel "Make 100 Claudes fight to the death". When Claude keeps giving you an answer you don't like, the Arena skill gives the same task to many sub-agents (100 by default). Each one tries it a different way, they attack each other's answers in a knockout bracket, a judge scores every match, and you get the one answer that survived.

Free and open source (MIT licence). No signup, no API key, nothing to connect.

Link: https://github.com/Jakeschincariol/arena-skill

What you need

• Claude Code (the terminal, or the Code tab in the Claude desktop app). It does not work in the normal Claude chat, because it starts sub-agents.
• Python 3.8 or newer on your computer. There is nothing to pip install.

Install (easiest way)

Open Claude Code, paste this and send it:

https://github.com/Jakeschincariol/arena-skill

Install this skill, then confirm /arena works.

Claude Code will copy the skill into your skills folder. Read what it asks to do before you say yes.

Or install it yourself (in a terminal):

git clone https://github.com/Jakeschincariol/arena-skill.git
cp -r arena-skill/skills/arena ~/.claude/skills/

Use it

• /arena: takes your last request as the task, and the answer you didn't like as the one to beat.
• /arena --quick write the headline for our pricing page: 16 agents instead of 100. Good for everyday use.
• /arena --agents 32 <task>: pick how many agents.

Claude may also offer the arena on its own when you say things like "that's wrong, try again". It asks you first before it spends anything.

Good to know

• It uses a lot of tokens. A full 100-agent run is 595 sub-agent calls over 7 rounds, and it's slow. Start with --quick (16 agents, 91 calls).
• It doesn't touch your files. Every sub-agent writes only inside a .arena/ folder in the current directory. Using the winning answer is up to you.
• Lots of approval prompts. Each sub-agent saves a file, so in normal mode you get one "allow?" prompt per file. Turning on accept-edits mode (Shift+Tab) for the run stops that.
• The judges are Claude too. The winner is the strongest answer the tournament found, not a guaranteed correct one. Give it a clear task and you get a better result.