I will be surprised if this goes much below $10, but even a smattering of play in Constructed will see this climbing pretty high
Tap, Tap, Revolution The name of the game is tapping Emmara for value
While it does scale down in the late game, a three-mana draw-three in the early to mid-game is great, and giving your opponents cards with it might not even be bad, especially if you run effects that profit off of exactly this
It's a great little common from the set, but it isn't great enough to be at a #1 spot on the list
The Power Nine When people talk about the most legendary cards in Magic, they usually mean the Power Nine, a famous group of nine cards from the very early days ( Alpha and Beta )
While on its face it seems like a major downside to playing the card, and hardly worth the cost - and it can be without the right cards in play - it pairs perfectly with the number of effects on Rise of the Floodborn cards that are triggered when cards enter or leave play, providing a easy way to put cards back in your hand, play them again and activate their effects