AZs are connected via normal user visible networks, you can just break those. They even provide examples, https://github.com/awslabs/aws-well-architected-labs/t

AZs are connected via normal user visible networks, you can just break those. They even provide examples, https://github.com/awslabs/aws-well-architected-labs/tree/master/static/Reliability/300_Testing_for_Resiliency_of_EC2_RDS_and_S3/Code/FailureSimulations https://github.com/awslabs/aws-well-architected-labs/tree/ma... Those are basic (don't cover flapping or glacial-speed slowdown degradation modes, some services only, etc) but a starting point at least that can be extended.