For the next ten days, you can get the Mehrunes Razor download for The Elder Scrolls IV: Oblivion free via Xbox Live. It's spelled out very well in this Bethesda Softworks update:

We're pleased to announce that we've worked with the good folks at Xbox Live to give away one of our most popular downloads for Oblivion - Mehrunes Razor - for a limited period of time. Starting this Friday, Dec. 22, Xbox 360 gamers will be able to download Mehrunes Razor for free. This offer is only for a limited time...from Dec. 22 to Dec. 31. On Monday, Jan. 1 it will go back to its standard price.

Normally a 250 point download, the free quest will give Oblivion owners the chance to earn Mehrunes Razor—a weapon with the ability to kill foes instantly—and discover 17 new magic items, all within the fringes of the Niben. Exciting! Michael McWhertor

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