A Revolutionary benefit that makes guards forget who you are once you have been out of sight for a while.
Blend into the Crowd is one of the benefits attached to the Revolutionary specialty offered to Carl in the Specialization booth. It causes guards to forget who he is once he has been out of sight for a while.
Carl reflects that he could really have used it on the third floor, and while he calls it great, he suspects the sixth floor is the only remaining floor where it would still be useful — part of his reasoning for choosing Agent Provocateur instead.
A stealth-adjacent perk Carl weighed and passed over.