On the GitHub page it lists these modes:

    Fault: Throw exceptions from methods that declare those exceptions
    Latency: Introduce latency on method-calls
    Nullify: Replace the first non-primitive argument to the method with null

The first two seem useful. The last maybe less useful depending on how you design your project. For example, I commonly disallow null to be passed as a method parameter for internal methods. External APIs will null-check, but all internal logic expects to never be passed null. Still might be useful since you can restrict the scope of it's instrumentation on a package level.