Mayael's Aria is a rare Enchantment card from Secret Lair Drop (SLD), collector number 1848. Current market price: $1.81, TCGplayer market prices via Scryfall.
At the beginning of your upkeep, put a +1/+1 counter on each creature you control if you control a creature with power 5 or greater. Then you gain 10 life if you control a creature with power 10 or greater. Then you win the game if you control a creature with power 20 or greater.