20200205-rundelayed-inheritance.cs

public class MyMonoBehaviour : MonoBehaviour {
    protected IEnumerator DelayedCoroutine(float delay, System.Action a)
    {
        yield return new WaitForSecondsRealtime(delay);
        a();
    }

    protected Coroutine RunDelayed(float delay, System.Action a)
    {
        return StartCoroutine(DelayedCoroutine(delay, a));
    }
}

public class Buff : MyMonoBehaviour
{
    public void OnBuff()
    {
        StopAllCoroutines();
        Debug.Log("buffed!");
        RunDelayed(2f, () => {
            Debug.Log("debuffed!");
        });
    }
}