PvP drop potential glitch
The glitch was activated by summoning a Beast of Burden familiar and storing high value items in it, then hopping to a free-to-play PvP world. The glitcher would then die 15-20 times, tricking the system into thinking they had died with the value of the items stored in the familiar. The glitcher would return to a members PvP world and kill players, obtaining high value drops due to the drop potential system.
The bug was in the game for some time before it was discovered.