I'm looking for ideas to go after a wizard who hides in a Mage's Magnificent Mansion. Let's assume he ducks into to escape combat.
Some possibilities:
1. Use a Wish/Miracle to enter the mansion.
2. Scry the wizard (if he doesn't have Mind Blank up) and use a Gate to enter. I don't see any way RAW to Plane Shift there.
Nothing easy or moderate level comes to mind, unless you can cast Dispel Magic on the door to end the spell early. I'm torn as to whether that would work. I lean towards "no."
It can be dispelled.
You can also try the social route, and be invited inside.
Ask your DM, it isn't explicit but he may allow some method of forcing open the entry.
A Magnificent Mansion is tough to adjudicate since it's both a spell effect and its own plane (more or less). Unless there's some explicit top-down ruling, pretty much any plan you concoct will depend on how your GM interprets the combination of spells involved.
I'm not sure a Gate would function since, as per the spell description, a Gate can be prevented from opening by "beings who rule a planar realm"; which the MM's caster pretty much is.
There doesn't appear to be anything preventing the use of A Plane Shift to get inside except for perhaps the material component. Since it has no listed cost, any spell component pouch should have whatever attuned fork you might need to cast the spell. Seems to me that a successful spellcraft check would allow the caster to pick an appropriate fork. The GM might very well veto that however.
Since there appears to be some viable lower level spells, using a wish or miracle would certainly seem sufficient to get inside.
A successful Dispel Magic would also seem sufficient to end the MM spell effect. I don't see any reason it shouldn't work if cast on the door's location.