I had it review a single, large commit with /code-review. It burned through over $50 in API calls, ran my account balance out, and output nothing.
The fable part appears to be that it's affordable by mere mortals. Anthropic support told me "too bad" when I requested a refund.
I think the fable it's referring to is the "Emperor has No Clothes" - if this is even slightly similar to the Mythos hyped up to be too intelligent to release, I'm quite disappointed.
If this was a step change, e.g a Opus 5, I'd be pleased, it's definitely an upgrade on some work, but it's nothing like anthropics apocalyptical marketing seemed to suggest
Almost the exact same thing happened to me when I first tried opus, one prompt no output cost $60 in additional usage
Combine that with it forcing to pay by tokens on June 22nd
You pulled the arm of the slot machine and discovered why they call it the one-armed bandit.