Bypass Your Validation Rules | Validation Rules | Formulas Superbadge Unit 

Create a Case validation rule that prevents users from changing a Case Status after it has been set to ‘Closed’. Create a custom permission that allows specific users to bypass this validation rule.
Create a Custom Permission:
Name: Bypass_Case_Validation_Rules
Create a permission set:
Name: Bypass_Case_Validation_Rules
Assign the Custom Permission to the permission set.
Create a Case validation rule:
Name: CASE002_Cannot_Reopen_Case
Give your validation rule a good description.
Build a formula that allows users with the Bypass_Case_Validation_Rules permission to bypass the validation rule.
Hint: use PRIORVALUE to see if the Status is being changed from Closed.
Error Message: Cases that are closed cannot be reopened [CASE002]
Error Location: Status