Reanimate Choosing a creature from any graveyard to revive back to the battlefield is a powerful ability
A quick search on Reddit will get you a lot of ideas on how to use Leyline of the Guildpact in Modern, and we're sure that more broken interactions will find their way into the format as time goes on and people get to playtest this card
What kinds of cards might you be able to pull in that box
This makes aura-focused payoffs like Brine Comber and Stormchaser Drake a bit worse and aura support cards like Cradle of Safety and Supernatural Rescue nearly unplayable
Every burn spell, card draw spell, spot removal, sweeper, stax piece, and mana rock would have a creature type like goblin, wizard, rogue, elf, squirrel, shark, fox, ooze, or ouphe