Henrikh Mkhitaryan proved influential as Jurgen Klopp's men grabbed four goals in 14 second-half minutes on Tuesday.
Things could have been much easier for Dortmund had Pierre-Emerick Aubameyang taken any of the three chances that came his way prior to the interval, but the Gabon international lacked his normal sharpness.
The lower-league hosts punished Aubameyang by opening the scoring in the 38th minute.
Tino Schulze found room in the attacking third before finding Dennis Lemke, and the forward made no mistake as he fired beyond Zlatan Alomerovic.
However, Dortmund turned on the style after the break, with the introduction of Mkhitaryan the catalyst.
When Edisson Jordanov levelled on 63 minutes, the Armenia international had already seen one effort hit the post.
Mkhitaryan did find the net three minutes later after neat work from fellow substitute Jonas Hofmann.
A mistake from goalkeeper Kevin Rauhut in the 71st minute enabled Mkhitaryan to set up Tammo Harder for Dortmund's third, and Oliver Kirch completed the scoring with a nice solo effort.
Dortmund continue their pre-season preparations with a match against Heidenheim on Saturday.
