[spoiler=Reaper of the Decks: Info] DARK/Fiend-Type Effect Monster/Level 8/2580/3030 DEF Lore: (Quick Effect): You can reveal this card from your hand, then target 2 or 4 Set cards on the field
But from the lot of packs I bought, every questionable pack has at least these 5 things in common

Ayara, First of Locthwain Ayara, Widow of the Realm Blightsoil Druid Briarblade Adept Compleated Huntmaster Creakwood Safewright Dawnhand Dissident Dawnhand Eulogist Deadbridge Shaman Deathknell Berserker Drider Duskwielder Elderfang Disciple Elderfang Ritualist Elvish Doomsayer Elvish Dreadlord Exquisite Huntmaster Eyeblight Assassin Eyeblight Cullers Eyeblight's Ending Gilt-Leaf Winnower Gloom Ripper Gnarlroot Trapper Haunt of the Dead Marshes Hired Hexblade Hunter of Eyeblights Infestation Sage Iron-Shield Elf Koma's Faithful Lys Alana Scarblade Maralen of the Mornsong Melancholic Poet Miara, Thorn of the Glade Moonglove Extractor Moonglove Winnower Nadier's Nightblade Nadier, Agent of the Duskenel Nightshade Harvester Plague Witch Prowess of the Fair Ruthless Winnower Scarblade Elite Scarblade Scout Scarred Vinebreeder Shadowheart, Dark Justiciar Skemfar Avenger Skemfar Shadowsage Thornbow Archer Thornmantle Striker Twilight Diviner Unscrupulous Agent Viconia, Drow Apostate

There's also some things about the card that I can talk about
This card is a sideboard staple for decks that want to deal with specific threats like Karn, the Great Creator or Urza's Saga, and its flexible enough to fit almost anywhere
You just need the former out on the field, Vivien in your hand and one red mana going spare