The Rock-esque approach that is so natural for this color combination would do well to have that sort of card filtering, as the risk with such archetypes is often drawing your cards out of order or suffering mana troubles
Any one of these effects could be built around individually, but good luck with building a deck full of smiling Pegasi with party synergies
I started with the question: "How can we know that 17 is generally the right number, and how can we know when it isn't?" But in reality, we can't really know for sure - none of these calculations have been super rigorous, as there have been many assumptions and approximations
This change would make the following cards and their colorshifted counterparts legal in prEDH despite being printed after New Phyrexia: (Clifftop Retreat), (Inspiring Vantage), (Needle Spires), (Nomad Outpost), (Snow-Covered Wastes), (Stone Quarry), (Sunbaked Canyon), (Sunscorched Divide), (Talisman of Conviction), (Wastes), and (Wind-Scarred Crag)