Hold onto your hats folks, because tonight kicks off the 2 night ‘The Flash / Arrow‘ Crossover event. This is going to not only bring the worlds of The Flash andArrow together, but we are going to get to see all the new characters that will be part of the new ‘Legends of Tomorrow‘ series which will premier January 21st on CW. What will happen when the hero’s face off against the immortal Vandal Savage? Check out the promo’s for tonight’s episode below, and then tune in to the CW tonight at 7pm central and find out! Join in the Conversation after the JUMP!