Magic the Gathering Scars of Mirrodin booster box contains 36 booster packs with 15 cards each. Scars of Mirrodin is the first set in the Scars of Mirrodin block. Distribution is 1 rare or mythic rare, 3 uncommon, 10 common, 1 land and a tip card. 
The set contains 249 black-bordered cards (15 mythic rare, 53 rare, 60 uncommon, 101 common, and 20 lands). The mythic cards have a red symbol and were introduced for the first time in Shards of Alara.

Look for the following Mythic Rares:
Elspeth Tirel
Geth, Lord of the Vault 
Indomitable Archangel 
Koth of the Hammer 
Liege of the Tangle 
Lux Cannon 
Mindslaver 
Molten-Tail Masticore 
Mox Opal 
Platinum Emperion 
Quicksilver Gargantuan 
Skithiryx, the Blight Dragon 
Sword of Body and Mind 
Venser, the Sojourner 
Wurmcoil Engine