Some are familiar

[Smarthuiyuan]

Hakkar would cast Corrupted Blood on players and it would damage them for approximately ten seconds. Players would disperse the effect to others when they got too near those infected. After the 10 seconds were completed, or players finished the boss battle, the harmful impact was supposed to finish. Only it did not.

A programming oversight allowed the debuff to disperse beyond the site of the Hakkar boss struggle and into the world at large. Hunter characters may summon and discount pets to fight in their side at will. Once ignored, all of the consequences on the pets are paused until it is known as back out again. In consequence, the pets could contract Corrupted Blood during the boss fight, disappear and then exhibit the symptoms elsewhere in the world map when they were summoned. There it might spread to other pets and players which came in contact with them.

Cities such as the dwarven city Ironforge and orc town Orgrimmar were overrun in hours. Non-playable personalities, who couldn't die as a result of particular coding, would also capture the effect, meaning any player who passed by them could get Corrupted Blood.

Once word got out, players searched frantically for information about what was going on.

"The world chat would explode any time a city fell," says Nadia Heller, an ex-World of Warcraft player whose persona lived through the incident. "We kept a close attention not only on our guild chat but on world chat as well to see where not to proceed. We did not need to catch it."

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