Leyline of Abundance is a rare Enchantment card from Core Set 2020 Promos (PM20), collector number 179p. Current market price: $1.81 (foil $3.61), TCGplayer market prices via Scryfall.
If this card is in your opening hand, you may begin the game with it on the battlefield. Whenever you tap a creature for mana, add an additional {G}. {6}{G}{G}: Put a +1/+1 counter on each creature you control.