The ability is quite strong, its basically much shorter timer on something similar in purpose as butterfly. You can multiply threats for 3 turns later, AND place them in advance to convenient position. While the cost is not low, it still might be quite moderate for the (range * strength) of the ability + built-in bishop1.5 . I am not completely against the ability, I'll just prefer it with short range ( != full board !), and maybe a piece that has it as main strength, not a bishop added to it. Similar to e.g. FrostMage, EarthElemental.