Matthew McConaughey and Idris Elba are taking their "Dark Tower" duel seriously.

The actors will playing the deadliest of enemies in the movie adaptation of Stephen King's "Gunslinger" novel series. In advance of the first trailer, expected to debut tomorrow, they both released teaser videos via social media playing up their characters' antagonistic relationship.

McConaughey's villainous Man in Black ominously promises "the Tower will fall" in his teaser:

Elba shot back with one of his hero, Roland Deschain aka the Gunslinger, declaring, "I don't kill with my gun. I kill with my heart."

And here's the official synopsis of "The Dark Tower":

Jake Chambers (Tom Taylor) is a young 11-year-old adventure seeker who discovers clues about another dimension called Mid-World. Upon following the mystery, he is spirited away to Mid-World where he encounters the lone frontiersman knight Roland Deschain (Idris Elba), who is on a quest to reach the 'Dark Tower' that resides in End-World and reach the nexus point between time and space that he hopes will save Mid-World from extinction. But with various monsters and a vicious sorcerer named Walter Padick (Matthew McConaughey) hot on their trail, the unlikely duo find that their quest may be difficult to complete.

"The Dark Tower" opens in theaters August 4.