In a crazy first-half it was the hosts who steamed into a four-goal lead after 24 minutes thanks to goals from Jordan Smethurst, Jack Brierley, with two, and David Hogg.
Slyne hit back after the break with Mark Murphy and Danny Dickson reducing the arrears to 4-2.
David Hogg soon had Hesketh Bank’s fifth but Ian Roe’s visitors weren’t done with Murphy on target for a second time as four goals were scored in six second-half minutes.
Ryan Teale seemed to have secured the three points with a 74th-minute sixth for Bank but goals from Jamie Hastings and Murphy’s hat-trick strike ensured it was an interesting finale at Station Road.
Richardson Cup finalists Garstang went down 6-2 at home to title-chasing Blackpool Wren Rovers, fresh from their own Lancashire Amateur Shield win on Wednesday night.
Tom Graham and Jack Smethurst, with a penalty, were on target for Lee Baker’s side who were always chasing the game at the Riverside.
They next face Charnock Richard in the Richardson Cup final at the County Ground in Leyland on Wednesday night.