These cards are not intended to be reprinted in normal tournament-legal paper Magic sets, which creates long-term scarcity
Of course, actually activating the freerunning cost is the conundrum that all of these cards present, but it's very easy to see a world where more Assassins and Changelings are printed
Mardu Impulse Draw Fire Lord Zuko 85%inclusion 135 decks 159 decks Neriv, Crackling Vanguard 6.7%inclusion 11 decks 164 decks The War Doctor // Clara Oswald 3.6%inclusion 6 decks 166 decks Dihada, Binder of Wills 1.2%inclusion 2 decks 166 decks Rograkh, Son of Rohgahh // Tymna the Weaver 1.2%inclusion 2 decks 166 decks Celes, Rune Knight 1.2%inclusion 2 decks 165 decks Bruse Tarl, Boorish Herder // Vial Smasher the Fierce 0.6%inclusion 1 decks 166 decks Isshin, Two Heavens as One 0.6%inclusion 1 decks 166 decks Mr
She supplies a drain for every creature you play for the rest of the game, and she lets you recycle your Fenlurkers and Freebooters for additional cards (again useful in a mono-black deck)
Progenitus cant be targeted by any spells or abilities
