You must ensure that your face-down spells and permanents can be easily differentiated from each other
The Rule Box for the Mega Evolution rules also has the Mega Evolution symbol on it

3 1 Blazing Bomb 1 Gaius van Baelsar 1 Garland, Knight of Cornelia (Foil) 1 Garland, Royal Kidnapper (Borderless Foil) 1 Geralf, Visionary Stitcher 1 Jecht, Reluctant Guardian 1 Jill, Shiva's Dominant (Borderless) 1 Immersturm Predator 1 Locke Cole 1 Matoya, Archon Elder 1 Namazu Trader 1 Prompto Argentum 1 Queen Brahne 1 Qutrub Forayer 1 Redcap Gutter-Dweller 1 Seifer, Balamb Rival (Borderless Foil) 1 Shaun, Father of Synths 1 The Emperor of Palamecia 1 Ultros, Obnoxious Octopus 1 Zell Dincht 1 Zenos yae Galvus (Borderless) Enchantment 1 Sidequest: Card Collection 1 Sidequest: Hunt the Mark Instant 1 Dreams of Laguna 1 Eject 1 Light of Judgment 1 Magic Damper 1 Stolen Uniform 1 Syncopate 1 Vivi's Persistence (Borderless Foil) Sorcery 1 Combat Tutorial 1 Cornered by Black Mages 1 Cruel Ultimatum (Breaking News) 1 Mega Flare (Borderless Foil) 1 Memories Returning 1 Relm's Sketching 1 Resentful Revelation 1 Retrieve the Esper 1 Travel the Overworld 1 Unexpected Request Land 1 Baron, Airship Kingdom (Foil) 1 Bloodfell Caves 1 Command Tower (Foil) 1 Dismal Backwater 1 Evolving Wilds 1 Swiftwater Cliffs 1 Temple of Deceit 1 Temple of Epiphany 1 Temple of Malice 1 Treno, Dark City (Foil) 1 Vector, Imperial Capital (Foil) 10 Island (4 Foil) 9 Swamp (1 Chocobo Track Foil) 9 Mountain (1 Chocobo Track Foil)

And if you put counters on five different dragons
Solved You may look at the top card of your library any time, and you may play lands and cast creature and enchantment spells from the top of your library.
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