The reported exploit of an invincible Wizard in Diablo 3 have been hotfixed by Blizzard.
A post on Blizzard forums details the hotfix:
We are currently rolling out a hotfix for a recent bug regarding invulnerable Wizards. We will continue to carefully monitor this issue and welcome anyone with information about bugs or hacks to submit a detailed report to our Hacks Team by emailing firstname.lastname@example.org, or by completing the Hacks Report web form. In your correspondence, please include any steps necessary to replicate the issue as well as any additional details you are able to provide.