The First Eruption is a rare Enchantment — Saga card from Dominaria (DOM), collector number 122. Current market price: $0.20 (foil $0.05), TCGplayer market prices via Scryfall.
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — This Saga deals 1 damage to each creature without flying. II — Add {R}{R}. III — Sacrifice a Mountain. If you do, this Saga deals 3 damage to each creature.