Gladehart Cavalry is a rare Creature — Elf Knight card from Duel Decks: Elves vs. Inventors (DDU), collector number 11. Current market price: $0.33, TCGplayer market prices via Scryfall.
When this creature enters, support 6. (Put a +1/+1 counter on each of up to six other target creatures.) Whenever a creature you control with a +1/+1 counter on it dies, you gain 2 life.