It was the Gareth Delany show at North County as the Leinster opener's powerful century ensured Premiership cricket for the Rathmines side in 2019.
Chasing a Rush total of 227, Delany's pyrotechnics saw Leinster race to victory in the 34th over, winning by six wickets.
Delany, whose hard-hitting approach for Ireland Wolves has led to calls for senior international recognition in the T20 side, hit 14 fours and 6 massive sixes on his way to a match winning 113 from just 82 balls.
He dominated an opening stand of 92 with Hugh MacDonnell (28) and added 93 for the second with overseas player Monil Patel (47) to all but end the match as a contest.
Allan Eastwood (2-40) was the pick of the Rush attack, which was blown away by Leinster's brutal assault.
Leinster had gone into the chase with all the momentum after Rush had collapsed badly when they looked set to post close to 300.
Skipper Neil Rock top scored with 80 from 83 balls (7 fours, 3 sixes), adding 118 for the 4th wicket with Tipu Gull (42).
However his dismissal in the 40th over proved the turning point, as Rush collapsed from 185 for 3 to 227 all out.
Their cause wasn't helped by four run outs, while Joe Carroll picked up 3 for 25, and skipper George Dockrell 2 for 40.
All credit to Leinster in showing their class in what is always a high pressure game, while commiserations to Rush who nevertheless can be proud of a season which saw them capture the National Cup, and their youth team the All Ireland U15 title.
At Balrothery, Leinster beat Rush by 6 wickets
RUSH 227 (49.4 overs; N Rock 80, S Gull 42, S Doheny 29, P Vishwanath 20; J Carroll 3-35, G Dockrell 2-40)
LEINSTER 231-4 (33.2 overs; G Delany 113, M Patel 47, H MacDonnell 28; A Eastwood 2-40)