So I wish to upload a recolor of the riftborn blob. Problem is, the art guidelines on the Custom Pet Images page states:

"Don't simply adjust the hue/saturation/colour of official artwork - this distorts quality/lines"

This has thrown me for a loop, so I need advice on what to do. Should I attempt to upload the recolored image?

i think it depends on how the resulting image looks. sometimes when you use filters/adjustment layers to drastically change the color/brightness/saturation of an existing image, the result can look... kind of bad! for example, let's say i wanted a purple glade bumbus, so i threw the image in photoshop and slapped on a couple of adjustment layers (without using blending modes to paint over any of the areas by hand). here is the result:

that uh... doesn't look very good, does it? the lineart looks pixelly and the colors are kind of jarring and mis-matched. but if the image is simple enough to begin with, or you know how to use adjustment layers properly, it's totally possible that your resulting image will look just fine.

Honestly it looks pretty to me. With all the flowers and all.

I do believe I used layers for my recolor. This is it below:

personally i think your overlay looks fine. i think that rule is really just there to caution against careless use of filters & adjustments by people who don't really know what they're doing. but especially on simpler images like the blob, there's less concern of things coming out looking to wonky.