Tonight saw another new promo released, check out all three below plus preview images.
"Worlds Finest" episode synopsis:
Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home.
The Flash and Supergirl crossover airs Monday, March 28th at 8pm ET on CBS starring Melissa Benoist and Grant Gustin.
The Flash and Supergirl preview images: