While the markdown percent isn't as significant as it is with Gaea's Cradle and Survival of the Fittest, the World Championships versions of these cards still offer a 20-50% discount to their original, black-bordered counterparts
Blocks were eventually shelved after Wizards realized the Two-Block Paradigm was problematic for a lot of reasons, mainly because of a lack of reprints and issues with developing sets
Damping Sphere limits Eldrazi decks by reducing their fast mana advantage and hinders Ruby Storm by increasing the cost of their spells
Im not sure why this needed to exist, but it provides possibly the best mana fixing in Commander this way
But since this always doubles your card pool for an effective two turns, the possibilities are almost endless
While its easy to identify the three players who might feel hard-done by in this scenario, its also fair to assume that many combo players in this scenario will also feel similarly deflated