Your search for "Wall of Diffusion 211" revealed the following:
Rowan, Scion of War - Promo Pack (PWOE) from Wilds of Eldraine, available at 401 Games Canada. Rarity: Mythic Rare Finish: Normal Artist: Magali Villeneuve Card Text:MenaceT: Spells you cast this turn that are black and/or red cost X less...