"The Flash" and "Arrow" are set for another TV crossover, and The CW has just released a new promo to prove it.

Check out the teaser below -- titled "Heroes Join Forces" -- which touts another two-part crossover between The CW's hit superhero franchises, starting on December 1 with an episode of "The Flash," called "Legends of Today."

You can catch "The Flash" Tuesdays at 8 p.m. ET, and "Arrow" on Wednesdays, also at 8 p.m. ET, on The CW.