Sudden Demise

Oracle Text

Choose a color. Sudden Demise deals X damage to each creature of the chosen color.

Card Rulings

10/17/2013 You choose the value for X as you cast Sudden Demise. You don’t choose the color until it resolves.
10/17/2013 Sudden Demise will deal damage to a multicolored creature if one of its colors is the chosen color.