Zone of Flame is a rare Enchantment — Aura card from Mystery Booster 2 (MB2), collector number 571. Current market price: $0.15, TCGplayer market prices via Scryfall.
Enchant zone (Battlefield, command, exile, and stack are shared zones. Each player has their own graveyard, hand, and library zones.) Whenever one or more cards enter or leave enchanted zone, Zone of Flame deals 1 damage to each opponent. (Tokens aren't cards.)