D&D 5E Mordenkainen's MOBILE Mansion? Opinions wanted

[Sunseeker]

I think we need a new spell: Mord's Mobile Home. But you can only summon it while in Mord's Trailer Park.

Typically I allow "magical doors" to be mobile while on a large enough moving object. So I would probably not allow the door to be "moved" while on a cart or a rowboat, or thing of similar size.

 

[TwoSix]

Attaching it a movable wooden frame would enable all sorts of Trojan horse style shenanigans. Which is exactly the reason you choose to play a level 13+ wizard to begin with.

 

[Jester David]

Well, when you get right down to it, the Earth is mobile, hurtling through space at many miles per second. If the location moves, I'd allow the doorway to move too.

 

[Jester David]

Do you interpret that way for all vehicles, or only of a certain size? If the spell can be mobile on a ship, could it be mobile on a rowboat? In the back of a horse-drawn cart?

(I'm not trying to trip you up; I'm honestly trying to work out the repercussions of ruling either way.)

Anything big enough to be a location. Sailing ship, lightning rail train, airship, etc.
Anything too big for 1-5 people or their mount to daily move. Anything big enough to live in and not just ride. Something with existing doors and rooms.

-edit-
this is a tricky ruling. It should work when you use the mansion while travelling, but not when trying to "move" the mansion. When you could easily sleep anyway but are choosing comfort and security, where moving the mansion is a side effect rather than the goal.

This is a good example of something that makes for a terrible RAW rule, because defining the terms is tricky. It comes down to individual DMs going "are they abusing the spell?"

 

[Mouseferatu]

Just for context--though obviously I didn't/don't want to limit the conversation to just this, or I'd have said so in the initial post--this whole train of thought began when I found myself wondering if one could use interdimensional magic spells to allow an entire party to travel inside an apparatus of Kwalish.

 

[Oofta]

A related question is: how would an immovable rod work? After all, unlike the mansion's opening, it specifically states that it is immobile.

If you state that it is truly immobile in respect to the earth, it becomes a missile traveling at a thousand miles an hour the moment you place it. Good luck trying to figure out what direction it would be going in.

I would rule that a rod would be stationary in relation to the planet, as if it had been a normal rod placed on the ground. Magic works in relationship to what we consider stationary.

Based on that logic I'd say you can't do a mansion on a boat.

 

[GreyLord]

So, there's no RAW answer to this, and that's fine. I'm looking for opinions and repercussions.

If someone were to cast Mordenkainen's magnificent mansion while aboard a vessel (such as a ship), would you permit the entryway to move with the vessel? Why or why not?

Ah, looks like someone already mentioned this...

I think it depends on whether you are on a flat earth which the universe revolves around, or if you are on a planet which revolves around a sun and a galaxy.

If the former...it could stay stationary as the ship moves.

In the latter, do you allow the entryway to move with the planet or not?

If you do, using the Laws of physics, allow the entryway to move with whatever object it has been connected to previously.

If not...well...the characters have bigger problems if they actually get to the doorway as now they are in space with no planet beneath them!

 

[Tony Vargas]

So, there's no RAW answer to this, and that's fine. I'm looking for opinions and repercussions.

If someone were to cast Mordenkainen's magnificent mansion while aboard a vessel (such as a ship), would you permit the entryway to move with the vessel? Why or why not?

A Ship (and I'm thinking an anachronistic age-of-sail three-masted Ship), certainly. I tend to think of a ship as a location. You'd have a 'scene' set "on board ship at sea," for instance. A Ship already has cabins, so this gives you a really big, luxurious cabin. Enjoy. A small open boat, or a cart, not so much.

It'd be a harder call with a covered wagon or enclosed caravan or a Viking longship.

Easier call with a cloud castle or a theoretically-moving scientific world that's a planet hurtling through space around a star or a mythologically-moving fantasy world on the back of a swimming turtle.

Just for context--though obviously I didn't/don't want to limit the conversation to just this, or I'd have said so in the initial post--this whole train of thought began when I found myself wondering if one could use interdimensional magic spells to allow an entire party to travel inside an apparatus of Kwalish.

That's just one of those things where you have to rule yes, just so you can rip off Yellow Submarine. (Not that the Portable Hole - possibly among other D&Disms - wasn't already ripped off from Yellow Submarine).

 

[Dausuul]

Just for context--though obviously I didn't/don't want to limit the conversation to just this, or I'd have said so in the initial post--this whole train of thought began when I found myself wondering if one could use interdimensional magic spells to allow an entire party to travel inside an apparatus of Kwalish.

I rule "yes" on the grounds of sheer awesomeness.

 

[Wednesday Boy]

Just for context--though obviously I didn't/don't want to limit the conversation to just this, or I'd have said so in the initial post--this whole train of thought began when I found myself wondering if one could use interdimensional magic spells to allow an entire party to travel inside an apparatus of Kwalish.

That's weird and cool enough that as a GM I would let it happen, regardless of the RAW. If the players tried to use that as precedence for iffy fun breaking shenanigans I would reign it in. (But even in those cases I could be swayed by the rule of cool.)