Blue
Ravenous Bugblatter Beast of Traal
No problem! I think the ideal way to disrupt the Pavlovian response to combat is for it to be dangerous enough that if the PCs charge in without care they might easily lose more XP than they gain. I.e. instead of removing the cookie, mix in some electric shocks. This is difficult to do with vanilla 5e however, and involves a higher PC death rate than what most people want - certainly compared to classic D&D where PCs might have only 1/3 - 2/3 chance of making it to the next level.
Agreed. That easier to implement in a system that supports longer term repercussions outside the dead/not-dead-and-soon-healed of vanilla 5e.