Batman: Arkham Origins - Cold, Cold Heart DLC South Gotham
After dropping down, head to the Northeast towards the Bat sign. Don't drop down on ground level once you get there.
Drop down on the metal ledges down below and stay there. You'll have to slowly make your way through the enemy numbers cause all of them are armed with guns.
Unfortunately the goons here move in a really weird way and chances are you'll get noticed eitherways. Make sure to always takedown the goons that are isolated.
If you get discovered, quickly move from one grapple point to another to confuse the goons and make them lose sight of you.
Once you've taken care of all the goons, climb down to the ground and activate your detective vision, then analyze the frozen guy twice.
After that a new marker will appear on the guy, analyze him again to reconstruct the crime and you'll find some drops of the mysterious liquid that was left behind.
Examine the drop and you'll receive a trail that you can follow with the Detective Vision, keep it activated and follow the chemical trail.
Follow the liquid trail all the way to the Southwest part of the city and you'll find a group of penguin's men near a van.
Drop down and glide kick one of the goons. There's a goon with a shield here, to take him down you'll have to stun him (B) then double press A followed by X to smash his shield to the ground.
Like electric baton holders, shield holders also can't be attacked from the front and their attacks can't be dodged either so keep that in mind.
After taking out the first group of men, re-activate your Detective Vision and follow the trail across the gates and to the alley on the left side. Climb the fence and you'll find more enemies.
Try to throw a Concussion Detonator at the goons below. If you can, make sure to aim for the guy holding a blade, but any other would do.
Considering you fail to knockout that guy with the blade, go for him first and jump behind him to get to the guy with the CW, but make sure to takeout the bladed guy first cause he's a pain to deal with while worrying about getting frozen.
Once you takedown the guy with the blade, start stunning and attacking the one with the CW, but don't let anyone re-take that blade from the ground. Use your Shock Gloves when they become available.
When you've dealt with all of them, approach the last conscious goon on the floor and interrogate him to get your next lead.
After obtaining your much needed information head up the catwalk behind the ice wall and proceed to the East towards Goth Corp.
Drop down from the metal pipe at the side of the GothCorp. building and Glide Kick one of the goons that are guarding the entrance to the building.
Immediately go after the guy with the CW and occasionally block attacks from the other goons.
After taking the goons down, approach the door to GothCorp and take out your Cryptographic Sequencer and aim it at the security box at the right side of the door.
I highly recommend using a controller on this as the vibration is the most obvious sign when you're looking for the codes. It's still doable without the countroller but a little harder especially with level 3 and level 4 codes.
Anyways to crack the code you just have to move the analog sticks around until the words stop shuffling and stay in a legible format. Get both right and the door will open.