Exception while paying a mana cost with Shimmering Grotto
Posted: 18 Jul 2015, 06:10I was casting Horde of Notions when the following exception popped up. I first tapped a mountain and a forest to pay RG, then tapped Smokebraider for UW, and then attempted to use Shimmering Grotto for W. The exception appeared just as I clicked on my final untapped mountain to pay for the Shimmering Grotto's cost.