This is about Invasion episode 6, “Bloodlines,” or where Flash will save with a mighty hand.
Impulse, or Bart Allen, non-impulsively goes to his past (our present) to end his dystopia. We get a full Flash family gathering out of it, including Jay Garrick! Barry Allen & Impulse team up to battle Neutron, who’s going to practically nuke St. Louis (or is that Central City?). Neutron is being overseen by mysterious aliens from the future. The threat’s over, but Impulse may not be in a hurry to return home. On an amusing note, Impulse’s trope-spouting and future-slang-hurling bests Kid Flash’s surliness.
B Plot: Clone Roy, Cheshire, and child go through minor goons in some Eastern temple-like thing to recover the original Roy Harper.
The voice actor doing Impulse lifted this episode from a humdrum plot. Do we need ANOTHER mystery, DC? Thank you, Peter David, for writing this quick flash of entertainment.