It has been reported that an exploit has been uncovered on the current third push of PTR 2.4 which Blizzard is looking into. Apparently it has been fixed according to Hortus. Shall you find evidence on PvP or PvE that the exploit still exists inform so to Blizzard at the following forum thread.
The exploit increases a player’s stats by stacking as many times as he has patience to duplicate the exploit. In short, a fan reported to have been stroke by a paladin for 17,000 Holy crit, and a 21,000 Crusader Strike. A druid Starfire one-shot an Arakkoa NPC for 16,000 damage.
Thanks, Damashi @ Aegwynn