Brackwater Elemental is a common Creature — Elemental card from Duel Decks: Ajani vs. Nicol Bolas (DDH), collector number 46. Current market price: $0.09, TCGplayer market prices via Scryfall.
When this creature attacks or blocks, sacrifice it at the beginning of the next end step. Unearth {2}{U} ({2}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)