Differential Notoriety
The five targets in the Meeting Adjourned mission are dispersed in a small room with many guards, which makes this mission seem like an unlikely candidate for anonymous poisoning. Fortunately, the developers made an unusual choice in the design of this mission: The room is not a high alert area. Instead, they elevated the awareness levels of the targets so that they behave as if you were Notorious, which is functionally similar to making the room a high alert area - except that the developers did not change the guards in the room correspondingly. As a result, the targets and guards behave differently in this mission, which is what I exploit in this mission design to poison all of the targets while remaining unseen (no yellow bars) to all of the guards.