I recall seeing some limited discussion about this in the last few weeks,
but no definitive answers:

Has anyone determined if the LVL 22 Anti-Magic Song actually works? I play
it (strings required) and I get the message "A static pulse washes through
you". My party and I all get the icon, but it doesnt *seem* to do anything
to harmful spell effects. Any qualitative data would be much appreciated:)

Lago Bardoon, 30th Rank Bard of Bertox