Remember, while every card that can transform has a mana cost (in fact, that’s how you tell it’s the front face), its reverse side has a brand new set of characteristics, including mana cost. In the case of the back face of a transforming card, that mana cost is… nonexistent. Therefore, just like a land card (which also has a nonexistent mana cost because it can’t be cast), its converted mana cost is zero. Unlike lands, however, transformed cards have a “color indicator,” the little dot in the typeline. This basically exists so that back face cards can still have a color even though they don’t have a mana cost. In the case of Ugin, this is good for you, because every “flipwalker” has a color indicator that matches its front side — so for the low, low cost of choosing “zero” as the X in its “-X” cost, and removing zero loyalty counters, you can exile all of them on the battlefield at once!
Today’s Rules Tip written by Jen Wong