As I understand it, when a spell targets something with MR, but doesn't have enough penetration, the target will feel the spell ping off his resistance and know something was cast.
So if I set up a ward against faeries, with a spell level of 40, and penetration of 20, a fae with MM of 30 would be potentially be affected by the spell, except that the penetration failed.. so it would feel it ping.
But, if I did the same ward with a level of 5 and penetration of 5, and then the same MM 30 fae passed over it, would it get a ping on it's MR?
In this second example, the fae's MM is too high for the spell level, so the spell wouldn't target it, and therefore there would be no effect for the fae to notice failing to beat his MR?
The spell doesn't choose who the target is - the target (ie. The thing the spell tries to affect) is anything attempting to pass through the ward. Thus the low level spell still pings because it is too low level to affect the target, even if it could penetrate.
Would that mean a ward against animals would ping against the fae's MR?
It could have huge impact if used right. Lure a high MM enemy into a low level ward which it doesn't notice due to lack of 'ping', then DEO it a few times and leave it trapped in there for you to deal with it at your leisure.
Yep. Magic targetted you, but failed to do anything. I'd say it's more than reasonable that you'd detect that. I don't think you'd learn anything more than that a spell pinged, however.
Serf's Parma here, but I was under the impression that DEO destroyed Might points, not Might Score. As such, the magic resistance doesn't decrease. Even if it did, your foe trapped in the ward will regain Might and thus MR in a few hours anyway.
P. 160 "the demon looses might equal to the spell's level" that seems more like score than points to me. There is an earlier statement "weakens and possibly destroys a demon" that seems to agree with this. A supernatural creature is not destroyed by running out of might points but would be if it runs out of might score.