Dependency Guard is a Gradle plugin that monitors and protects against unintentional dependency changes in JVM-based projects. It creates baseline files of project dependencies for specified configurations and compares current dependencies against these baselines during build execution. When unintended changes are detected, it fails the build and provides a clear diff of what changed, allowing developers to either re-baseline for intentional changes or investigate problematic dependency drift. The plugin supports both simple list format and hierarchical tree format for dependency reporting, with the list format being recommended for CI usage due to less noise. It integrates with Gradle's lifecycle by automatically attaching to the 'check' task and provides clear commands for creating and updating baselines.