Curtains' Call

Instant

Undaunted (This spell costs less to cast for each opponent.)
Destroy two target creatures.

2016-11-08:
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.
2016-11-08:
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.
2016-11-08:
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.