Collector Boosters return with Theros Beyond Death (with a slightly tweaked formula). Blake has all the details you need to know here.
Theros Beyond Death Booster Box
In secret, Sauron forged a booster—one far more powerful than those owned by Elf, Dwarf, or Man. In this Collector Booster, Sauron sealed away the most incredible cards to grace Middle-earth: foils, Showcase cards, Borderless cards, and more.
Magic The Gathering Collector Booster Pack Lord of The Rings Tales of Middle Earth
Phyrexia: All Will Be One Collector Booster Pack – Fable Hobby
MTG Theros Beyond Death Collector Booster Box
LOTR MTG? : r/Albany
Returning to Theros Beyond Death Collector Box Opening MTG
NOW TAKING PRE-ORDERS MAGIC THE - Game Nerdz - Mesquite
Theros: Beyond Death Theme Boosters - MYTHIC!
Promo Pack: Theros Beyond Death - Da-Planet
Theros Beyond Death - MTG Wiki