Sheoldred, Whispering One [The List] Hidden Fates Set: Kaladesh Inventions Type: Artifact

Set: Kaladesh Inventions Type: Artifact Rarity: Mythic Cost: {5} Whenever an opponent draws a card

Set: Unlimited Edition Type: Sorcery Rarity: Uncommon Cost: {1}{G} Return target card from your graveyard to your hand

Set: Foreign Black Border Type: Creature — Angel Rarity: Uncommon Cost: {3}{W}{W} Flying

so this is one of several places where players can get a rare or mythic rare in a single Set Booster

The ravine is great

Sheoldred, Whispering One [The List] Hidden Fates Set: Kaladesh Inventions Type: ArtifactSet: The List Type: Legendary Creature Phyrexian Praetor Rarity: Mythic Cost: {5}{B}{B} Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.) At the beginning of your upkeep, return target creature card from your graveyard to the battlefield. At the beginning of each opponent's upkeep, that player sacrifices a creature.