Curtains' Call

Oracle Text

Undaunted (This spell costs 1 less to cast for each opponent.)

Destroy two target creatures.

Card Rulings

11/8/2016 You can’t cast Curtains’ Call without two creatures to target. If one becomes an illegal target after you’ve cast Curtains’ Call, the other will still be destroyed.
11/8/2016 Causing an opponent to lose the game after you’ve announced that you’re casting a spell with undaunted and determined its total cost won’t cause you to have to pay more mana.
11/8/2016 Effects that reduce what you pay to cast a spell don’t affect its converted mana cost. Sublime Exhalation’s converted mana cost is 7, regardless of how many opponents you have or how much mana you spent to cast it.