There is no such thing as a 50% het, but there are 50% possible het, which means it has a 50% chance of being a het and a 50% chance of being a normal.
So if you were to breed a spider to a 100% het clown, the offspring would either be spiders or normals and all would have a 50% chance of being a het. You could then breed the spider females back to the male 100% het and if they proved out, then there is a possiblility of producing spider clowns.
A black pastel is a codom, so a black pastel bred to a spider could produce black pastel bees (not sure what the name is.)
Hope this helps.