You can add rules, actions, and other task list to a task list.
You can add a rule to a task list by either right-clicking on the task and selecting New | Rule or clicking the Rule button from the Workflow ribbon within the New ribbon group.
You can add a action to a task list by either right-clicking on the task and selecting New | Action or clicking the Action button from the Workflow ribbon within the New ribbon group.
You can add a task list to a task list by either right-clicking on the task and selecting New | Task List or clicking the Task List button from the Workflow ribbon within the New ribbon group.