Seven cards are a huge advantage and have the power to completely change the game in your favor
Deep-Cavern Bat Deep-Cavern Bat is a proactive play that locks a card from your opponent, besides giving you information
The prices for the most valuable Shimmering Skies won't stay consistent over time, but the overall picture of which ones hold value is likely to remain similar
Zareth San, the Trickster is a five mana 4/4 with flash that you can put into play for four mana if a Creature you control is unblocked when attacking
Existing sleeves, binders, grading cases, storage boxes, tournament equipment, and packaging would all become obsolete
It also made Standard very boring by being way too pervasive