Update: The Quest for Packs grand prize has been modified to include $1200 in cash. "We’ve heard hopeful adventurers voice concerns that the idea of winning the Grand Prize is a daunting prospect," community manager Daxxarri wrote in a forum post. "That’s not in the spirit of a proper quest, so to help smooth your way, we’re making the rewards sweeter."
Blizzard doesn't come right out and say so, but the reasonable assumption is that the money is meant to cover the taxes that might be applicable to the prize. The approximate retail value of the grand prize is $6564 (not including the $1200 added on) and as specified by the rules, "All federal, state, local taxes and customs duties associated with the receipt or use of any prizes are the sole responsibility of the winner."
As this Reddit thread explains, that could add up to a hefty and entirely unexpected shot in the wallet. The winner could decline the prize to avoid that expense, but that's only an option if the recipient is aware of the potential tax hit in the first place. The added cash component may not cover the bill entirely, but it will at least take most of the weight off.
Blizzard is wrapping up Hearthstone's Year of the Mammoth with a "Quest for Packs" sweepstakes that will reward the grand prize winner with 3000 card packs—1000 packs from each of the expansions released during Year of the Mammoth (Journey to Un'goro, Knights of the Frozen Throne, and Kobolds & Catacombs)—plus the Lich King's Helm (the real one, apparently) and a package of Hearthstone swag.
Also up for grabs are 1000 Mammoth Card Bundles, a new bundle featuring ten card packs from each of the Mammoth expansions, and 50,000 Mammoth Packs, containing one pack from each. The Mammoth Card Bundle will also be available for purchase for a limited time when the 10.2 update goes live.
As for that helm, "We found it in his desk after his internship ended," Blizzard said. "Now we’re passing it on to you! Yes, the very same helm worn by the Lich King as he stalked the halls of Blizzard Entertainment could be yours!"
The Quest for Packs gets underway at 9 am PT/12 pm ET on February 1 and will run until the same time on February 14. During that time, each daily quest completed earns one entry into the drawing: You can claim one per day, and a maximum of 14 in total, and you do not have to be a citizen of the US to take part, which is nice, although there are some geographical restrictions. Full details are available in the contest rules.