Moving stuff by moving other stuff

[Tellus]

@ezzelino

@Tellus

Lifted from the originating thread.

@ezzelino

Note that there's a fundamental difference between lifting, and holding up something that's already up. Lifting a mountain requires a pretty high level spell. It's canonical that a level 20 spell allows a grog to hold up a mountain that's tossed onto him (assuming the mountain does not crumble under the stress).

Could you point me to that spell please?

Ward the grog against stone. Base 5, +1 Touch, +1 Conc, +1 stone. Note that the ward is affected only by the size of the grog, not by that of the mountain (see the other ward examples, e.g. Aquam in the corebook).

Why not let the mountain shatter around him, entombing him in stone?

@ezzelino

Suppose I can push/pull/hold with Rego magic an object that's within the size limits of my magic (let's say a basic Individual, with no size modifiers); and suppose the object is solidly attached to another, larger object that would definitely be outside the size limits of my magic. Can I indirectly push/pull/hold the larger object by pulling/pushing/holding the smaller one?

Sure, sort of.

For example, can I magically hold up a rope that fits easily within T:Ind, if a load that doesn't is hanging from it? Can I levitate the bottom of a large chest filled with gold coins, indirectly pushing up the whole chest, if the bottom would require no size adjustments but the chest as a whole certainly would (ok, I may need T:Part to target just the bottom, but that's a separate issue)?

Bad example, as you mention yourself.
In this case, +1 part or +1 size comes to the same.
If it is full of gold... not sure about that.

Would you let me levitate a tree (+3 sizes IIRC) by lifting only the core (+1 part)?

Can I hold a large horse in place by holding immobile its leather harness?

Immobile, no. Force it to stay in place until the harness tore, probably yeah.

I'm particularly interested in:
a) canon references of what can and cannot be done in this sense (e.g. I vaguely recall some fyling castle from MoH where the only "flying" thing was a thin stone disc at its bottom).

Fairly vaguely
That one's in Legends of Hermes, chapter 6.
It has a +3 for size, and the wording "The spell causes the castle to fly at the running speed of a horse." LoH, p. 123

b) problematic consequences of allowing or disallowing this "indirect action"

It kinda messes with the whole idea of sizes, sending us back to the 4th edition where a starting magus could make a flying castle easily enough.
Would need a friend to make it invisible/disguise it as a cloud though.

c) any elegant solution that "works", seems consistent with the RAW, and is easy to adjudicate.

Generally I'd disallow effects that levitate something based on T: Part. That's certainly easy, and works.
Indeed, I thought I'd provided a solution back in [url]catnip & garlic], stating that

@Tellus

Basically, I'd expect base ReAn to be able carry about the mass of a Size +1 animal - a pony to wit.
The fact that you are carrying a Herbam entity (the cart) or a Corpus entity (grogs) or even Terram entities (weapons and armour) should make things harder, not easier.
So yeah, if you're going to be lifting that much on a single rope, prepare to toss in a few magnitudes for "lotsa powar"