Charged item idea (and another MR question)

Immobilizing Arrowheads ReTe 10
R: personal, T: individual, D: diameter
The enchantment of these lead cored, barbed arrowheads is trigged by the impetus of the arrow running out once shot. At that point they become completely immobile for two minutes. This thoroughly hampers the movement of any creature stuck with them unless it rips itself free with a 9+ STR+SIZ roll doing twice as much damage as the initial arrow hit.
base 1 (lead not moving is natural), +2 affect metals, +1 diameter duration, +2 ad hoc for solidity.

The MR qustion is, of course, what happens when the arrows strike a creature with MR? I presume they will wound as normal initially as the enchantment is inactive at that point but:
Will the enchantment activate at all without penetration - it's not relying on a signal from outside?
If it does activate, will it be effective without penetration - after all it's not trying to move the arrowhead against the MR protected flesh?

1.) Charged items, like enchanted items, are resisted by MR from making contact with the protected being, even if not targeted by a spell of effect. Thus, a magic sword which allows the holder to fly will not strike a magus unless the sword penetrated MR.

Your arrowheads would need to penetrate MR to wound.

2.) Once the arrow is lodged, the effect will occur as normal. In order for it to rip the flesh of the victim, however, it must still penetrate MR. This may mean the victim is unable to move at all, or it may mean that s/he escapes easily with the arrowhead sliding out of the wound, if s/he fails to resist the preliminary attack but does reisist the arrowhead once it is lodged in his/her body.

3.) You can avoid the MR problem by enchanting the shaft, but not the head, of the arrow. This takes an aditional magnitude, as the effect is now R: Touch, to hold a lead arrowhead touching the arrow shaft for diameter duration.

4.) There have got to be better ways to spend a season.

So you don't agree with:

That depends on whether your archers can protect you and hunt your enemies significantly better with one shot stop capability.

I don't know it is an interesting question. Can mages walk through walls made with magic? If they run into one really fast are they hurt?

Still given how the effect works I would say it needs to penetrate, as it is being held in place by magic and not mass as is the case with the CrTe wall that say a flying mage runs into.

But the mass of the CrTe wall is magic.

The best way to think of MR is as an invisible barrier which prevents magic and magical things from passing through it. A magus cannot "run through" a CrTe wall; all MR can do is prevent the wall from harming the magus by falling on him (it would break around the magus) or similar events. A magus can climb a magic wall, if he so chooses, can hold a magic sword (though the sword blade will not break his skin if resisted) can ride a magically created horse, though the horse would never, quite touch him.

there's a good list of examples in ArM5

As a cheat sheet, some good rules of thumb are:

-- Resisted magic CAN bear weight, if solid.
-- Resisted magic solids CAN halt movement
-- Resisted magic solids CANNOT impact a magus, so a magus will not be harmed by a wall falling on him.
-- Caveat to the above, a magus falling onto a magically hard surface can still suffer falling damage, as MR halts his fall as suddenly and violently as a stone wall could (Medieval people knew that violent motion in itself could cause harm, like from violent shaking. Its not unreasonable that in this scheme of physics a sudden stop can be understood to cause internal injury.)
-- Falling onto spikes, a magus might suffer impact damage, but the spikes will not puncture the skin.