http://www.worldofballpythons.com/mo...-black-pastel/ there you go, mystic and phantom appear to be quite identical in every regard, just like lesser and butter.
i would still prefer butter/lesser:
http://www.worldofballpythons.com/mo...pastel-lesser/
on its own or in combos, butter or lesser is just stronger than mystic or phantom, so in my opinion mystic or phantom make most sense when you want to go for non-white super forms and BELs. stuff like mystic potion, purple passion, super phantom.
but its a matter of taste, both combos look really nice. another option would be black pastel mojave.