Two countries had long standing hostilities based in both cultural and religious differences, but as time passed, these hostilities had cooled to a non-aggressive, yet stern dislike. During this period, the hostilities became more covert, and instead of sending hordes uneducated farmers with improvised weapons, the countries would secretly engage each other with magicians, either in small groups or as solo operatives.
One effective tactic was to send parties of illusionists, as they could work as a collective in concealing their identities and could strike with impunity unless specialized mages were placed in their way.
One of the countries developed a salve that would allow illusions to be counteracted using various means, all without the need to tie up a valuable magician with defense by allowing mundane soldiers to penetrate illusions.
Full Item Description
There are three primary ways the Butter of Disbelief can be applied.
Firstly, any magician, illusionist or otherwise, that ingests the butter is unable to create or sustain any illusions until the butter passes from their system, typically 8-10 hours, perhaps longer, but this time can be shortened if the magician takes measures to purge this from their system.
Secondly, the Butter of Disbelief can be applied topically, rubbed on the skin, of defender. Used in this manner, the butter prevents any physical reaction to illusions. A soldier thus protected could walk through illusionary fire and never face any danger of being burned, where an unprotect one would feel the false fire as if it were real. The illusionary fire would still be perceived, with every effect the illusion carries with it, except touch. The subject can see, smell, hear and taste illusions, but not feel any illusion. This is the most common application of the salve.
Thirdly, the salve can actually be applied to one or both eyes. It is every bit as uncomfortable as having butter placed in your eye, and further, objects viewed are seen as well as one could normally see out of an eye full of butter. The benefit of treating an eye in this manner is that the eye will not perceive any illusions. Commonly, only one eye is treated, leaving the subject to perceive both illusions and reality and alert other to the differences.
Applied to the skin or eyes, the salve lasts approximately four to six hours.