In magic slang, a Bear is any creature with the same converted mana cost and size as Grizzly Bears, Ashcoat Bear, Balduvian Bears, Bear Cub, Forest Bear, and Runeclaw Bear: Two power and two toughness for two mana
Celebrate your crossover adventures with exclusive items, including a foil promo card and an oversized D20
Horde of Notions and Gisa and Geralf operate similarly to one another, as you can cast your tribal cards directly from your graveyard at either their cost or a fixed cost
Maybe Aetherworks Marvel is too strong for its own good, but I would guess that the primary reason to ban more, in the short run, would be if players were just seeking new puzzles, new challenges
Rares seem to be about 1 in every 10 packs
Vow of Flight Enchantment Aura Enchant creature Enchanted creature gets +2/+2, has flying, and can't attack you or planeswalkers you control