If the maker and check concept is followed in the organization you can appoint a reviewer at the time of task creation.
To submit any task for review just select the task and click on bulk action>>>> Submit for review
You get this window box to type any remark and then click on confirm.
You can also choose any new reviewer from the list.
After that just type confirm and submit for review.
The reviewer will get a mail and flash notification and he will be able to see the task in his Review board