Quick terminology check to avoid confusion - tagging is for spending determination, compelling is for awarding/gaining determination. Players can't tag their own challenges (like enemy) to spend determination, only their qualities. GMs can *compel* a player's challenges to award them determination. GMs can also compel a player's qualities to award them determination. Players can tag another character's qualities AND challenges to spend determination.
Usually when I (as GM) compel a player's enemy challenge (and award them a determination point), it's to get them to immediately drop doing something else to focus on the actions of their sworn enemy. They can always refuse the compel, but that costs them a point of determination instead. But if the NPC villain merely shows up at the same location as the hero, for example as a guest at an event like a big charity ball the hero is also attending, I usually don't award determination just for that. Not until the villain takes some antagonistic action.
--- In firstname.lastname@example.org, Icosahedrophilia <d20@...> wrote:
> Dear friends,
> What does it look like in practice to tag an Enemy challenge? Do you award the hero a point of Determination if you use their Enemy in an adventure? How have you tagged Enemy to good effect, or had Enemy tagged for you to good effect?
> Chris Heard
> Icosahedrophilia Blog and Podcast