One of my magi has a spell that turns him into a bear. He used this to attack a giant faerie slow worm - which raised the question if he had to penetrate its Magic Resistance with his shapechanging spell in order to actually be able to hit it. Thankfully another magus had drained some of its Might before, so this wasn't actually an issue at that moment, but the basic question still remains open for future application. I'd tend towards "yes, you have to penetrate" - opinions?
The official answer depends upon the nature of the shapechange, but for hermetic spells the answer is "Yes" see HoH: MC, pg 22...
As long as it's a magical shapeshifting (and AFAIR, all are magical except the heartbeast), it must penetrates.
The real question is, by transforming himself, would he make it impossible for the Giant worm to touch him?
Can this effect things generally, give de facto magic resistance against direct attacks from Faye, demons and magical beasts?
"Ha! The Dragon cannot eat me! I'm green!"
It's not a ward. They can affect you, but you can't affect them.
How can you tell the difference?
An enchanted rock can't hit a faerie... what if a faerie with a death-wish runs at a magic boulder running down a hill. Will there be impact?
Part of the pink-dot dillemma.
It's the pink dot dilemna, and that's why it's up to each opinion.
Since i don't want to interpretate the rule allowing you to cast eyes of the cat (little MuCo) and become unapt to be hit by anyone since you can't beat their MR with no penetration : i say, try it. And be smashed ^^.
There is a difference between hitting and being hit in Ars. The faerie will take the same damage as if he had run into a stationary boulder. The boulder will stop unless the combination of the slope and its size is such that it cannot balance between the hillside and an immovable faerie.
AFAIK there is no weight limit of magical material that MR can support. I can see someone testing this by nailing 3 fairies to a solid floor to form a stable base and forcelessly creating increasingly heavy rocks over their heads. One could use 3 very small castings of Aegis of the Hearth instead but that's pretty expensive.
I'm with you: Arcane Limit of the Giant Dragon who Will Eat You.
Just makes sense to be aware of the flaws in the system.
I'm not sure. I'd say that the faerie takes no damage at all. Just like a faerie falling onto an immobile, pointy magical rock (that does not bypass the faerie's resistance) is not harmed by the rock.
Wrong - the point cannot penetrate so the fairy takes no extra damage from being pierced but it does take the same damage as if falling the same distance onto a flat surface. This is explicit in the core book. I don't see what you are finding so hard.
And it has nothing to do with the pink dot problem - that arises from consistently applying a(n overly broad IMO) rule about which objects count as magical objects for purposes of MR.