House Rule: Task Resolution

[Dimirag]

I strongly recommend the use of another approach instead of the "change your selection" one.

[Finieous]

Again, not sure I'm following. As I said, I'd just want to be clear on what the player wants to be good at, and then we'd do that. Perhaps I'm making it sound more complicated than it is.

[Dimirag]

I wouldn't allow a background that just overlaps a class.

You'll been forcing a player to change his concept or selected BG because mechanically overlaps with the selected class, to me that is a fatal error, is like saying "soldiers or town guards can't become fighters".
I would just let the players use whatever BG they want, they might don't gain extra proficiencies but they could also bring interesting things like the ex guard being proficient in hearing or the ex soldier being proficient in military tactics.

[Finieous]

For most players, I presume some overlap would be fine. Watchman + Fighter seems an obvious combination, and by choosing it, the player would be telling me he wants his fighter to have some skill in investigation, interrogation, streetwise, practical knowledge of the town and its major players, etc.

On the other hand, if a cleric player chooses "priest" as his background, I'm thinking that's too much overlap, so I'd ask for more information about what the player is looking for. Maybe he wants to be a bishop, with a leadership role in the church, some skill in politics, diplomacy, intrigue, etc., or maybe he wants to be an inquisitor, or a prophet, or a mystic or whatever. I would expect that, in almost all cases, the player hasn't really intended to choose a background that perfectly overlaps his class, so I'd just want to make sure I understand what he's going for when he says "priest." And whatever he's going for, that's what we'd do.