I have inputted the code ‘ABBADON-BLACK’ into accounts.atoma.cloud, however the Tattoo Cosmetic seems not to have appeared in my cosmetics. I have been waiting since soon after the code went live, checking in daily.
N/A
Steam
ID: King in Yellow
Constant (100%)
Could you include the URL to your Steam profile also, please? 
Absolutely 
My apologies for the delay, I’ve had a look at your account I can see the key has been redeemed successfully and the items appear to be in your inventory. You’ll want to visit the Barber-Chirurgeon and select ‘Modify Appearance’ → ‘Body Tattoos’.
Thank you very much.
I think I’d misunderstood what the tattoo was, since I was under the impression the tattoo was actually a shirtless Upper Torso cosmetic option (like the pre content-drop bug).
I can see it now. Sorry about all this .
I hope you have a lovely day.