We mentioned previously this all-foil Secret Lair drop had something to do with Phyrexia: All Will Be One. That's because the product contains four Planeswalkers in the Borderless Manga special treatment—plus, these Planeswalkers are only available in this Secret Lair and do not appear in the main set.
Four Planeswalkers in the Borderless Manga/Anime special treatment:
• 1x Foil Ugin, the Ineffable
• 1x Foil Sorin, Imperious Bloodlord
• 1x Foil Sarkhan, Dragonsoul
• 1x Foil Nicol Bolas, Dragon-God