Board Thread:Administrator's noticeboard/@comment-37.8.203.159-20130201130647/@comment-6271162-20130202034202

Actually, I am pretty sure that it is an intended feature. You still have to go to the so-called "danger zone" (Yep, we all love you, Rumble) because it cost some mana and leaves your shield on cooldown.

Also, I think that the description of Thresh's abilities which was given out when he was released also covered this, but I not quite sure to be honest.