Then it's up to them to handle hundreds of cards and you get to walk out with money in your pocket
You were probably subconsciously influenced by Cosmic Encounter
If this creature's emerge cost was paid, instead create X of those tokens, where X is the sacrificed creature's toughness
Almost all of them have their niche in Standard
Reforge the Soul Time Ebb Write into Being Land: 14 Island 7 Mountain Bonders Enclave Desolate Lighthouse Forge of Heroes Forgotten Cave Hall of Oracles Lonely Sandbar Reliquary Tower Remote Isle Rivendell Rogues Passage Shivan Reef Smoldering Crater Steam Vents Sulfur Falls Temple of Epiphany Tyrite Sanctum Life, Backwards Without some form of deck manipulation, Rivers first ability isnt much different from normal card draw through a randomized deck, except your top deck is physically safe from mill
Since there's no sideboard, you may want to consider maindecking some artifact or enchantment hate, especially if those are themes of the format