Stronghold Arena is a rare Enchantment card from Dominaria United (DMU), collector number 110. Current market price: $0.23 (foil $0.14), TCGplayer market prices via Scryfall.
Kicker {G} and/or {W} (You may pay an additional {G} and/or {W} as you cast this spell.) When this enchantment enters, you gain 3 life for each time it was kicked. Whenever one or more creatures you control deal combat damage to a player, you may reveal the top card of your library and put it into your hand. If you do, you lose life equal to its mana value.