Unlock: Complete Complications, Use Michael
Bonus Requirements:
Unmarked – Finish the mission with minor damage received.
Kill Chain – Neutralize 7 aliens within 10 seconds.
Go to Legion Square and follow the marker. Basically, just Rambo your way across the mission. Utilize the unlimited-ammo chaingun, starting against aliens on the ground and later on against aliens above you. Concentrate first on enemies on the ground that approaches you, then later on aliens up above the structures. Strafing is the key to staying safe. Finally, if you got grabbed by an alien, shake the left stick to get yourself free.