"Star Trek: --------------"
25th Century Alpha Quadrant. A Dyson Sphere appears suddenly without explanation or hails to neighboring ships. The sphere's hatches open while hundreds of small pod-craft leave the shell of the Sphere and begin firing, taking out several Klingon & Starfleet ships assisting Cardassia Prime to rebuild following the Jem Hadar bombardment. The Starfleet-Klingon convoy cannot track & lock onto that many targets & destroy them simultaneously, leaving the convoy decimated. The podcraft begin to maneuver into landing patterns on Cardassia.
31st Century Starfleet
"Chef" Daniels notices the Temporal Incursion & signals for an agent to correct the 'oversight'.
29th Century Starfleet
Captain Braddox of the Temporal Vessel Relativity notices the breach & diverts course to intercept.