Not every Dragon works well with others, and some don't even share the same color types
There are a number of cards you can't use in Explorer: Expressive Iteration Field of the Dead Geological Appraiser Karn, the Great Creator Kethis, the Hidden Hand Leyline of Abundance Lurrus of the Dream-Den Nexus of Fate Oko, Thief of Crowns Once Upon a Time Teferi, Time Raveler Tibalt's Trickery Underworld Breach Uro, Titan of Nature's Wrath Veil of Summer Wilderness Reclamation Winota, Joiner of Forces MTG Alchemy banlist Alchemy is another digital format for MTG Arena, which is based on the Standard card pool
Blacksmith's Skill
Triskaidekaphile is probably worth a slot since putting lands into your hand at instant speed could creep you up to thirteen cards and the win condition, and other than that, the card draw ability and no maximum hand size are going to be useful
Being a ninja makes it useful in more than just illusion decks, and we like cards that can be used in more than one place