I'm creating an extremely difficult challenge requiring advanced regex techniques by combining multiple complex patterns:
1. Highly varied ISBN formats with different separators and validation codes
2. Cryptocurrency addresses (Bitcoin, Ethereum) with specific format requirements
3. Base64-encoded strings with specific pattern prefixes
4. Complex password patterns with specific character requirements
5. IPv6 addresses with compressed notation and embedded IPv4
6. OAuth tokens with specific patte... (truncated)