They have 12 or 13 cards instead of 15, and their card distribution is pretty complicated: 1 art card (5% chance of a signature variant) 1 land (15% chance of a foil land) 6 connected cards 35% chance of 5 commons, 1 uncommons 40% chance of 4 commons, 2 uncommon 12.5% chance of 3 commons, 3 uncommons 7% chance of 2 commons, 4 uncommons 3.5% chance of 1 common, 5 uncommons 2% chance of 6 uncommon 1 showcase variant 2 wildcards of any rarity 49% chance of 2 commons 24.5% chance of 1 common, 1 uncommon 17.5% chance of 1 common, 1 rare/mythic 3.1% chance of 2 uncommon 4.3% chance of 1 uncommon, 1 rare/mythic 2.6% chance of 2 rare/mythics 1 rare/mythic 1 foil of any rarity 1 token/ad card with a chance of being a card from The List You basically sacrifice the boosters ability to be used in a Draft for a chance at multiple rares
A 3/3 flying creature for three mana is already something
We've also got a bunch of fun Colorless support cards like amazing draw with Mystic Forge, one-sided wipe with All Is Dust, cheeky countermagic with Warping Wail, and whatever the heck Endbringer is
Depending on your creature count, he grants your entire team extra power and abilities that make them harder to block
Memories Returning is essentially a draw three for 4 mana, which is particularly good in the blue/red archetype