'Supergirl' season 2 spoilers news: Crossover episode to feature Supergirl in Arrow's Star City

The second season of "Supergirl" is expected to feature many crossover episodes where other DC superhero series such as "The Flash" and "Arrow" will make an interesting appearance on the show. The first season of "Supergirl" has already seen the red speedster on its universe, but the only question is when will the Green Arrow make his presence felt in Kara Danvers' world.
Comic Book reported that the plans are already laid for the anticipated crossover of "Supergirl" and "Arrow" for their new seasons this year. In fact, "Arrow" producer Wendy Mericle revealed that she and her creative team have already come up with a "loose plan" for the crossover. Instead of one, there will be four-day crossover episodes that will be shown in December. Still, these plans can still change later on, with the possibility of one crossover episode each show within a week.
"Supergirl" entered her new home in the CW network, opening plenty of doors for crossover with other DC comics series.
While the fans can expect another "The Flash" and "Arrow" crossovers, Mericle revealed that she is most excited for her show's crossover with "Supergirl." The producer wants to see Kara Danvers' smile lightening up Star City for a change, as Green Arrow's area of interest has always been subjected to dark forces over the years.
"I mean, I love Supergirl. How can you not? I love all those guys, but she's the first female superhero appearing in her own [modern] show!" said Mericle.
iDigital Times said that before the much-awaited "Supergirl" and "Arrow" crossover happens, the world of Supergirl must first be formally introduced in Green Arrow's universe. Nevertheless, this was already shown as a possibility when Barry Allen visited Kara's alternate Earth last season, suggesting that people from Barry and Oliver Queen's shared universe can visit Supergirl's world anytime next season.