Sylbert Rundin miniaturizes an advanced weather dirigible and Team Flash arrives with a plan to embiggen Cisco and Ralph in episode 4x12 "Honey, I Shrunk Team Flash".
The team arrives to help A.R.G.U.S. and the police stop some terrorists but one of the them manages to set off a nuclear bomb which the speedsters desperately rush to stop before it destroys the city in episode 4x15 "Enter Flashtime".
Cayden James gives Black Siren a device to stop her from being tracked before flying off on his jet in episode 6x04 "Reversal".
Cayden James and Black Siren break into the internet vault and work to destroy it in episode 6x04 "Reversal".
Black Siren meets with her contact to hand over the fingerprints and get the next name on her list in episode 6x04 "Reversal".