You get an emblem with "Whenever you cast a red spell, this emblem deals X damage to any target, where X is the amount of mana spent to cast that spell." Chandra's first ability uses the stack and can be responded to, even if no targets were chosen
Palantr of Orthanc either gives you a card, or you mill some cards and someone takes damage equal to the total mana value of the cards milled this way
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
cards in the world, and it will most definitely sell to someone else in no time
2 Trainer promo has been put up for sale