Tomorrow and Wednesday, Flash and Arrow will have their midseason finales, both of which (if past seasons are to go by) will be pretty dramatic, and shift things into high gear for the back half of the season.
As such, both finales have gotten extended trailers, along with synopsis for both.
Flash: Running To Stand Still:
“When Mark Mardon AKA The Weather Wizard (guest star Liam McIntyre) returns to break Leonard Snart AKA Captain Cold (guest star Wentworth Miller) and James Jesse AKA The Trickster (guest star Mark Hamill) out of Iron Heights, Barry must stop these rogues from taking over Central City during Christmas. Meanwhile, Joe and Iris meet Wally West (Keiynan Lonsdale).”
Arrow: Dark Waters:
“After the city is attacked again, Oliver makes a bold move against HIVE. Malcolm checks in on Thea and leaves her with a warning. Things take a horrible turn when Damien Darhk (guest star Neal McDonough) retaliates in a brutal manner at Oliver’s mayoral holiday party.”