800 MSP today.
Four other games discounted are BloodForge (600 MSP), Gotham City Impostors (600 MSP), Real Steel (400 MSP), and The Expendables 2 Videogame (600 MSP), which all get the 50 percent off treatment. If you'd rather exchange money instead of time to have your Expendables instantly maxed out and all game content unlocked, the Full Access and Upgrade pack is down to 120 MSP. Also on the discounted DLC front is Cold Stream for Left 4 Dead 2. The pack includes the fan-made campaign of the same name, along with the four original maps from Left 4 Dead, and goes today for 280 MSP.
Also, today is the last day of Xbox Live's holiday-long sale. Should you want in, we've got the full list of those discounts right here.