Damn Vulnerable DeFi
The reference for offensive DeFi mechanics: flash loans, oracle manipulation, governance. Each level is an attack contract you write against an intentionally vulnerable target.
damnvulnerabledefi.xyz →Ethernaut
OpenZeppelin's leveled wargame on classic Solidity vulnerabilities. Ideal for a first structured pass through the offensive side.
ethernaut.openzeppelin.com →Capture the Ether
Fundamental challenges on how the EVM, randomness and signatures actually work.
capturetheether.com →Why legal practice matters
The same skills that find and prove a vulnerability are valuable and legal in bug bounty and audit contests. Writing an exploit against a live contract you do not own is not — it is illegal in most jurisdictions and on-chain traceability makes anonymity fragile. Practice on CTFs, then get paid on bounties. See Bug bounty.