Aquitect's Defenses is a common Enchantment — Aura card from Lorwyn Eclipsed (ECL), collector number 44. Current market price: $0.19 (foil $0.23), TCGplayer market prices via Scryfall.
Flash Enchant creature you control When this Aura enters, enchanted creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.) Enchanted creature gets +1/+2.