During the "DeFi Summer of 2020" there was a period of time where new Smart Contract exploits were reported on an almost daily basis.
If you want to learn how the infamous DeFi hacks worked and how you can take out a Flash Loan to manipulate Oracle price feeds you should definitely check out "Damn Vulnerable DeFi".
Protip: If you get stuck, not making any significant progress you should check out the OpenZeppelin Forum where community members share and discuss their solutions.
- @tincho