I still remember the one person who sneaked in Mount Hyjal in vanilla and met a blizzard blocker. For those of you wondering. They put these in as an additional safeguard for content they have in development but not released, usually because they use it as an experimentation field. Level 60 mobs with no attacks, 3 HP and a huge amount of XP and skill points were the norm in these sealed areas. They are a Storm Giant model that's REEEALY big, have an area wide aggro range and one attack that hits for roughly 100k damage with an unblockable trait and an attack speed of 1.00. They also sit with an HP count of more than any known mob by at least 3 to 1. If you're lucky you might get one hit off, but I doubt it. I think at best you have time to go "crap".
Poor guy was pissed he couldn't rez and the response from the GM's was effectively "tough ****, you weren't supposed to go in there."