Reanimator decks aiming to cheat out a Griselbrand would be massively strong, particularly in casual brackets where cheap interaction is at a premium (either because they are Game Changers, or they are just straight up expensive cards to own)
Tournament Demand English boxes are in higher demand across competitive Western markets, where official tournaments require English cards
With minimal effort you can create several infinite combos with his token generation ability, drawing tons of cards and quickly amassing an army
Do any include Palladium Myr, Endbringer, or Ulamog's Dreadsire
Using one of these legally requires that your deck conform to both its ink types, which some may consider to be a restriction
Third Exception to the Rule of Four - ACE SPECs Like Radiant Pokmon, ACE SPECs are extremely powerful cards that are limited to just a single copy of any one ACE SPEC in your deck