Champagne x Ghost x Spider

[Slicercrush]

The way we refer to co-dom, dom and such is just how the single mutant gene looks in heterozygous and homozygous forms. Other genes have no baring on it. It being allelic proves that there is zero reason for the super spider not to exist, as the locus doesn't have any issues.
If you can make super blackheads, you can make super spiders, and ignoring all other evidence, we can still ask what's the logical conclusion based of this alone. It's lethal.

^^^ This

Along with the fact that most neuro issue morphs (such as woma, for example) when bred together can have really terrible side effects, it really isn't surprising. Look at pearls (Woma x Woma) which is lethal as well, though I do remember seeing something along the lines of one living, atleast for a little while, using Hidden Gene Womas bred by NERD, but I would consider that a completely different case.