This thread either belongs to the skinning/texture forum or General Development, depending on how this result was achieved. In Tides of Blood, a characters has an ability that casts a regular cloud that is in black instead of the default blue. Color tinting does not seem to work on the model.
Q : How is the Black Cloud Animation done? I suspect either a blp file addition or trigger, or something I am still yet unaware of.
I take it you are talking about Dragonhawks' Cloud... I don't know how it looks but tinting won't work because it is particle effect. They extracted the model and changed particles color to 0,0,0,0.
I don't know how to change particle color via MDL, but you could also change the particle's texture by making it darker. You'll have to use a modified version of the particle mdx, with the apropiate texture.
I took the cues and used this program to change the particle's colors : http://www.wc3sear.ch/?p=Tools&ID=100. Total addition to file size was 1kb. Really worth it.