Lunar Force
Oracle Text
When an opponent casts a spell, sacrifice Lunar Force and counter that spell.
Card Rulings
7/13/2016 You can’t choose not to sacrifice Lunar Force.
7/13/2016 You sacrifice Lunar Force even if the spell’s already been countered, perhaps by the ability of another Lunar Force, or if the spell can’t be countered.
7/13/2016 The spell will be countered even if Lunar Force can’t be sacrificed, most likely because it has already left the battlefield. Casting a spell in response to an opponent’s Lunar Force’s triggered ability is generally a bad idea.
Or Sun Titan even.
Seems pretty bad to me.
Though I'm sure it still has its uses...
It'll probably be okay in Hanna and Zur EDH decks, though.
What really makes me happy, though, is the combo with Opalescence and Assault Suit (assuming there isn't a "if you do" clause in there that missed the translation). Counter a spell? More like counter ALL the spells!