Assume there is a troll guarding a bridge (for all bridges need trolls). Instead of attacking the troll, the party found some intrigue way of bypassing the encounter. I'm happy with it and award them full XP for the combat.
Now, a session or two later, the party comes back and kills the troll. Should they get the XP again?
Since this is hypothetical I don't know the reasons for killing the troll. Would the reason matter?
- Quest to kill the troll given by local lord
- Party wants to "farm XP" so they go hunt it down later with some justification-dance of their actions
- Absent member of the party returns, and disagrees with leaving the troll alive, etc.
Best Answer
The reason only matters if it matters to you.
XP is awarded for challenges overcome. Thus, if the troll presents a challenge both times, then yes, you should likely award XP both times.
So lets imagine that the troll guards both sides of a bridge. You have to cross both ways. The first time, you outsmart the troll, but make not allowances for the return trip. On the return, the troll is wise to your intellect and attacks. You should certainly get XP for both sides, as the troll presents a challenge coming and going.
However, if the troll is outsmarted, and then your party goes out of the way to kill him and steal his stuff, that may be something you don't want to reward (and honestly, may be something to talk to your players about outside of the session if that kind of thing isn't what you want in your game).
Basically, if the troll is an impediment to your hero's success twice, then yes, award XP twice.