Dear Sodales, after a long hiatus, I am dipping back in Ars Magica.
For a future play, I am building a mage that wants to build a moving hut (mostly made of wood) on giant size chicken legs (she is a Tytalus maga that want to create a BabaYaga personae).
How would you adjudicate the enchantment ?
Option 1: ReHe of the right magnitude (no need to discuss the exact magnitude, I can figure out that one), considering the legs more like an colorful way of showing the effect of the spell. Technically, a ReHe can move the hut, and with the right magnitude can even make it fly, so the legs are only for "decoration" purpose or could be added through a simple illusion (CrIm).
Option 2: ReHe, but by crafting wooden legs, possibly with some form of mechanical contraptions, the enchantment get a rather large Bonus for appropriate shape and form (+10 ?). However, since the bonus is limited to the MT of the mage, it is unlikely to be fully used unless crafted by a senior mage or a Verditius specialist.
Option 3: The enchantment create legs out of the hut structure, legs that are able to carry the hut. Probably a Mu(Re)He(An) of rather high magnitude considering the size and strength for the legs to carry the hut.
Regardless of the option, the enchantment will have "maintain the concentration" (to avoid a sudden collapse of the hut if the mage is distracted), yet requiring concentration to make it move.
Additional question: how would you tackle to have autonomous legs - specifically, the mage will give a direction or a place to go and the legs will do the rest to the best of their abilities, without endangering the hut and its content ? Are we looking at Heron's secret from Automata ?
Thank you for your future input.
Have a look at MoH p.44 Talisman: Gwidion's Riding Tree. "place to go" is tricky still - as Gwidion's tree doesn't really have a mind. So you might need a variant of p.139 Calling the Council of the Trees to summon an independently mobile tree, convince it to carrry the hut and repeat that every month.
Good suggestion OneShot!
The combination of Read Surfacce Thought and The Movement of a Man with a linked trigger sounds like a nice option, that fits within the rules. I was definitely not looking forward the path of rediscovering Heron's secret. I know Tytali love challenges, but it seems a bit far fetched just to build a Personae.
There's the ReHe 10 guideline in the core book "Make a plant or thing made of plant products move with purpose and intelligence, without requiring your constant control."...
I was going to suggest the ReHe Base 10 as well. However I would recommend including some number of Complexity Magnitudes in the spell. Without some degree of them, the effect would be limited in its capabilities (compare 'Bookstand of Hespera' which has none against 'Tireless Servant' which has two, Covenants page 121). You also most likely want Unlimited uses per day, unless you are limiting it to a couple of "follow me" activation per day.
If I was personally building such an enchanted item I would go with a more complex Invested device. Re(Mu)He Base 10, P/C/S, item maintains concentration, Linked Trigger, Unlimited uses for level 48 with the Muto used to allow it to uproot itself and form chicken legs as a +1 requisite. Then add in a MuHe(Me) Base 4, P/S/S, Environmental Trigger, 2 @ day, for level 29. This would give you a hut with Cunning, with that Cunning being able to direct the movement. Not combat capable (unless it manages to step on someone) but you could tell it something like "walk down the path to the lake, circle around to the north side, and sit down facing the water". The cunning would allow it to respond to unexpected changes as well.
Degree of capability and any requirements for Complexity are YSMV, but generally the combination of giving something wooden Cunning linked to a movement effect makes for very capable independent mobility.
I know people have good suggestions for fixing everything - but I figured I would add in a random-as-heck idea I had for a completely different approach. For variety. For SCIENCE!
I'll flesh out this idea when I'm not on a coffee break, and have my books.
Instead of animating your house, you could do the exact opposite, and transform an animal into a hut with legs. This means the hut has a base level of intelligence, trainability and perhaps affection for its master. You also could consider the possibility of transferring the brain of a loyal steed into the house, similar to the mind transfer spells in Core.
This probably is a much more complex way to go about it, but I thought it would be fun to mention.
Thank you for all these valid answers... especially, the core rule guideline... .
The hut will be designed to support the mage Personae, so I don't think it will have much stuff in it, and definitely not a lab (thinking of the comment of Raccoonmask).
I will see how I can make it cheap to build as the mage is not going to invest the time into building a solid Herbam knowledge. Since she has Spell Binding, maybe she will toy with some more simple spells she could easily acquire that can - at least temporarily - be sustain by an Herbam spirit.