Carnivorous Death-Parrot, Vile Bile, The Fallen Apart, Paper Tiger, Scissors Lizard, Rock Lobster, Double Header These Un-cards are considered mainly for pauper cubes since their power to toughness isnt special in cubes that allow for rares, but four power and a decent toughness for four is actually pretty hard to find outside of a few cards like Rhox Brute, Wildheart Invoker, and Windrider Eel (which is actually a 4/4)
As for the big spells, the first thing Id turn to is extra turn spells
I always assumed that shadowless were Leftovers from the first big batch of cards printed for 1st edition
If you copy something like Alrund's Epiphany or Time Warp youre suddenly so far ahead youre basically just playing an I win card, especially when youre getting multiple extra copies for free
MM: Designing Universes Beyond sets is an interesting challenge because it flips the worldbuilding on its head
You should know that legendaries are typically quite specialized and focused on supporting a single archetype