A utility Matchbox shader for Autodesk Flame, Flame Assist, Flare, and Smoke that premultiplies or unpremultiplies a fill based on a matte. Handy for using right on the timeline as a Timeline FX prior to a 2D Transform to deal with unpremultiplied logos and things (typically PNGs.)

While Autodesk supplies a matchbox called 'PremultiplyOnBlack', it doesn't pass the matte through which makes it useless on the timeline (and creates messier schematics in Batch/BFX since you have to feed it the input matte for it to operate, but have to connect the original matte to anything downstream.)

Grab Premultiply from the Logik Matchbook site.