Successfully complete level 1

Successfully complete level 3

Successfully complete level 5

Kill Gorrell

Upgrade both slots of a weapon in the Single Player Campaign

Kill an enemy with every weapon in the Single Player Campaign

Kill 250 Chimera in the Single Player Campaign

Kill 1000 Chimera in the Single Player Campaign

Kill 50 Chimera by detonating their heatstacks in the Single Player Campaign

Kill an Impaler

Kill any combination of 18 Impalers or Executioners

Kill the Leviathan