Bax remained silent and listened to the formation of the plan. His master, during the latter phases of his training, pointed out to him that a plan is like a journey; it can go as expected or it may not. Being able to adapt in unpredictable situations is an important talent, especially in an assassin.
"Is the Archbishop proof against poison also? Is it his habit to employ a taster?"
Powerful humans are known to do this on occasion.