Silent But Deadly
Stealth kill 10 Enemies with the Striker Crossbow
10/25/2011
5:48:41 PM
Very Rare 8.0%
Silent Partner
Damage the same enemy in Cooperative Mode for 100 kills
10/15/2011
10:08:44 AM
Rare 20.7%
Medusa
Freeze 5 enemies at once and destroy them with a blast of the Cryogun's secondary fire
10/13/2011
4:43:52 PM
Very Rare 8.5%
Good Fences
Don't allow any counter-attackers into the Washington Square base
10/13/2011
4:37:02 PM
Ultra Rare 2.9%