You can inject custom logic into predetermined stages of the IaaS machine life cycle by using vRealize Automation Designer to directly edit the state change workflow stubs and, optionally, call out to custom vRealize Orchestrator workflows.
The workflow stubs are being replaced by the event broker workflow subscriptions. They are still available, supported, and they can be used, but expect them to be removed in a future version of vRealize Automation. To ensure future product compatibility, you should use the workflow subscriptions to run custom workflows based on state changes. See Configuring Workflow Subscriptions to Extend vRealize Automation.