Anti-mage and more: herbs, metals and substances.

[flammos200]

I am also of the belief that a Lightslayer would be trained how to resist the Light, and not other magical forces. In fact, one of the major weaknesses of Lightslayers is that they are so focused on defeating Lightwielders that they're not good at fighting everything else.

It's part of the class's balance, just like a Demon Hunter is great against Fel, but not at all good at other stuff.

[Kira13]

Alright, alright, after long discussions with muhaha (and apparently others, via him), I've understood that there ain't any substances that could dampen or hinder magic. Furthermore, I have decided to keep my Lightslayer just a Lightslayer.

Thank you all for your help and opinions!