Edge of Eternities has plenty of strong cards, and the ones that always have a rare art treatment make up the most valuable cards in the set
At time of writing, there are only two known commons that reward this unnamed mechanic: Arena Trickster, which turns from an unexciting Hill Giant into a Rampaging Baloth (and can continue to grow), and Naiad of Hidden Coves, which allows you to play two Vexing Gulls on turn four
If you choose not to play a card with madness when the madness triggered ability resolves, it's put into your graveyard
For nearly three years, I almost exclusively played Stoneforge Mystic decks across all the formats I was playing at the time
Many abilities of plane cards affect all players, while many others affect only the planar controller, so read each ability carefully