I was able to pick up a couple more parallel cards from the 2018 Panini Illusions set. These cards feature a modern player, and an old school player, who have something in common.
In this case, it's Ezekiel Elliott and Herschel Walker. Here is the green version, serial numbered to 99:
Next is the black version, which is serial numbered to 25.
I'm still lacking the pink version, which is serial numbered to 75; and the purple, which is a one of one, to complete the subset.