Blizzard just announced that, in addition to having banned 120,000 malicious accounts, they will be reverting Death Knight character creation limits to what they originally were, meaning you will not be able to create a DK unless you have a level 55 character on your account already. 

Death Knights (Source)

Greetings,

Over the past few weeks, we’ve taken actions that removed almost 120,000 malicious accounts from the World of Warcraft ecosystem, including both Wrath of the Lich King Classic and Classic Era. This is in addition to our usual, ongoing banwaves, which often include actions against tens of thousands of accounts per week.

As a supplement to these recent actions, we want you to know that as of next week’s regional maintenance, we will be returning the original Death Knight character creation restrictions to Wrath of the Lich King Classic. This means that unless you already have a level 55 character on your account, you will be unable to create a Death Knight. We felt it was very important for the launch of Wrath of the Lich King classic to give anyone who wanted to hop into this iconic expansion the ability to do so with as few barriers as possible. Allowing every account access to Death Knights– even if they did not meet the historic requirements –was important. However, now that the initial launch period has passed, we no longer wish to allow the unrestricted creation of Death Knights on brand new accounts. It’s a tempting vector for malicious actors to use to get into the game and start exploiting very quickly.

We hope that this helps slow the proliferation of malicious behavior in Wrath of the Lich King Classic. It’s important to keep in mind that as long as there is a demand for gold and other services that players are willing to pay real money for, these malicious actors will keep coming back. Please– never hesitate to report suspected cheating such as buying and selling gold for real money, automation, and advertisements for power leveling or any real-money sales in chat. Your reports greatly help our efforts to take actions that improve the game.

Thanks to everyone who has commented on this issue over the past several months, and thanks to everyone who helps by reporting suspicious activity.