10 Atarka, World Render Another Dragon that synergizes with attacking Dragons, Atarka, World Render is a bit more aggressive than its counterparts
The 2.4x markup is almost entirely explained by the Charizard ex SIR

Advanced Search Sets Random Syntax A Trail of Teacups Aerie Ouphes Afterburner Expert Aftermath Analyst Agyrem Akoum Firebird Alesha, Who Smiles at Death All Suns' Dawn Altanak, the Thrice-Called Anarchist Ancestral Communion Antler Skulkin Arclight Phoenix Ardent Elementalist Artificer's Dragon Artisan of Kozilek Asgardian Inspiration Ashnod's Harvester Aspect of Mongoose Atzal, Cave of Eternity Aurora Phoenix Avengers Quinjet Balustrade Wurm Bloodfeather Phoenix Blossoming Tortoise Bogardan Phoenix Boseiju Reaches Skyward Bygone Marvels Canoptek Tomb Sentinel Cauldron of Souls Centaur Vinecrasher Chamber Sentry Charmbreaker Devils Circle of the Land Druid Claim // Fame Clay Revenant Coati Scavenger Codex Shredder Colfenor's Urn Combat Courier Convenient Target Corpse Cur Craving of Yeenoghu Creeping Renaissance Critical Hit Crop Sigil Curse of the Fire Penguin Curse of the Fire Penguin Dakmor Salvage Daretti, Scrap Savant Dawn-Blessed Pennant Deadwood Treefolk Deathmist Raptor Deeproot Wayfinder Desecrate Reality Dragon Breath Dragon Fangs Drownyard Temple Druidic Ritual Earthquake Dragon Eccentric Farmer Edgewall Inn Elder Pine of Jukai Emeria, the Sky Ruin Erinis, Gloom Stalker Eternal Witness Everquill Phoenix Everquill Phoenix Eye of Ojer Taq Feasting Troll King Fiery Mantle Firestorm Phoenix

Interestingly, while this agrees well with the samples from @burpies and Derium (see the introductory post for their raw data), which show 65.2% and 63.2% secret rares respectively, my own sample is kind of an outlier with only 56.1% of the cards from that sheet being secret rares
on stage at a live show Think of the last time the headliner card from a Magic: The Gathering set featured a villain
On top of those, there are also Japanese-only No Rarity versions of the Base Set Charizard