Curtains' Call
Oracle Text
Undaunted (This spell costs
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.
Compare with Unholy Hunger, Flesh to Dust, and Murderous Cut. You will (hopefully) have at least one opponent, meaning this card costs the same to hard cast, and only gets cheaper in a multiplayer game, but it kills TWO targets as opposed to one + minor utility.
Even if we think of it in terms of Murder, it's basically a double-Murder that doesn't waste an extra card and is cheaper to boot.
'Cause sometimes you need to kill two things. Not everything, not one thing, but two things. And this card is perfect for that.