Finally, CW just dropped the first teaser trailer of "Supergirl," "The Flash," "Arrow," "Legends of Tomorrow" crossover event called "Heroes vs Aliens." Felicity Smoak is absolutely super excited about the heroes' team up.

Ahead the CW's big superheroes collaboration which kicks off in less than 3 weeks, the network has released its first official trailer for the four-part story. In the clip, Barry Allen "The Flash" introduces his kryptonial pal Melissa Benoist's Kara Zor-El "Supergirl" to the rest of his heroic friends Green Arrow, White Canary, Firestorm, and on.

The "Heroes vs Aliens" trailer showcases the first superheroes meet up, like the fans of the DC, Felicity already dubs this as the "best team up ever!" While there is no doubt on that, it's better to watch it in action and possibly there are more twists to happen as the crossover event take place.

The four-night crossover premieres on November 28^th with Supergirl's new episode serves as the primer before the story truly begins in "The Flash." According to IGN, Barry Allen's series will be the beginning of the "Heroes vs Aliens" crossover; the middle story will be carried out in "Arrow" and will end in "Legends of Tomorrow." As per executive producer Marc Guggenheim, it's a "three-part crossover" with four series involved.

Meanwhile, the "Supergirl," "The Flash," "Arrow," and "Legends of Tomorrow" crossover storyline features the superheroes team up in battling against an alien race called the Dominators. The alien invasion previously irked the Legion of Superheroes in the late 1980s DC crossover "Invasion!" according to TVLine.

Additionally, the big bads of the crossover will be "mind-controlling space invaders alarmed by Earth's surging population of metahumans." So it's exciting to see how the "best team up ever" in CW will ward off these aliens back into the space.

Are you as psyched as Felicity for the CW's "Heroes vs Aliens" crossover? Share us your thoughts on "Supergirl," "The Flash," "Arrow," "Legends of Tomorrow" team up.