The more text a card has the better it is
I highly recommend mana sinks and instant-speed tricks to help synergize with Jorn's mana-refreshing abilities, allowing you to attack with the team and play tons of cards from hand every turn, while also giving the team vigilance and Wilderness ReclamationWilderness Reclamationing your lands so you can AetherspoutsAetherspouts or Mystic ConfluenceMystic Confluence or Pull From EternityPull From Eternity at a moment's notice
An MnG deck usually has two colors, so pick the two colors you have the most cards in as this will generally give you the most options
Each of the planes many districts is home to an exotic creature that, when bound to its rider, becomes a formidable racing foe
A decent flying beater outside of white and blue is valuable for putting the opponent on a clock
In a slow enough format it might prove very good, but it costs five mana, which is kind of bad