Leyline Immersion is a rare Enchantment — Aura card from March of the Machine: The Aftermath (MAT), collector number 71. Current market price: $0.75 (foil $0.56), TCGplayer market prices via Scryfall.
Enchant legendary creature Enchanted creature has ward {2} and "{T}: Add five mana in any combination of colors. Spend this mana only to cast spells."