Ordeal of Nylea is a uncommon Enchantment — Aura card from Theros (THS), collector number 170. Current market price: $0.32 (foil $0.98), TCGplayer market prices via Scryfall.
Enchant creature Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice this Aura. When you sacrifice this Aura, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.