NMs are immune to Plague (aside from Fafnir, he's the only NM I've ever seen plague land on) and thus Lowing would be an absolutely horrible proc spell. I have no idea who started circulating the rumor that it's a VW proc, but over countless hours of VW on BLU and through the use of common sense I can confirm with 99.99% certainty that Lowing is not a proc spell.