Leyline Immersion and Heroes' Podium let you accelerate and double-down on your legendary synergies
The reason why I dont have The Scarab God any higher on the list is because it is still a two-color legendary creature, making it hard to see widespread play
It has better support for its theme, better value overall, and better cards
More often than not, that splash card will just rot in your hand while you wait for the right mana
The rest of this list has focused on creature token generators, but the noncreature tokens of MTG can be just as deadly
Changing the as-fan of rarities (that is, the count of each rarity of card you'd expect to see when you open a booster), introducing more variance in slots, adding in more "outside" cards, all impact how the set plays and thus requires us to change how we build the set