Elemental Bond
The power-three threshold is the entire pivot of this design. Green has always had the easiest time fielding fat creatures, but it has historically paid for its card advantage in clunky one-shot effects: a Harmonize here, a Garruk activation there. This turns the color's natural curve into a draw engine without asking for any extra mana once it resolves, because the typical green deck is already overflowing with bodies that clear the bar. Where blue's card-advantage enchantments tax instants and sorceries, this rewards the thing green wants to do anyway, which is deploy threats. The three-power line is the cost: it deliberately excludes the mana dorks, one-drops, and utility small fry that would otherwise turn the effect into an unconditional draw-on-cast machine, so the trigger arrives bundled with battlefield presence rather than chip value. That tension (you only draw when you commit a real threat) ties the card advantage to the board state green is supposed to win through, and stops the engine from ever being free. It also stacks: nothing limits how many of these you control, and each one fires on the same entering creature, which is where the effect tips from grindy value into a genuine refill problem for whoever is trying to trade with you one-for-one.
