An easy way to get this is to have Tal Ratha as your N'Erud World boss.
When you talk to him before the boss fight ask him about him wanting to eat you. He has a pretty serious kink, don't shame him.
And then agree to let him eat you, again, no shame if this is your thing.
After this very easy fight, perhaps easier than the normal fight against him. You will get the alternative drop. But this is not the reward.|
To get the reward you need to return to McCabe and have her craft the item. So make sure you have at least 1000 scrap, and some Lumenite on hand.
As soon as you craft the item, the achievement will pop.
Here is an excellent video from AbbyHour showing this. Giver her some likes if you use this method.