Neptune never came out of the blocks and they were duly punished by their Dublin opponents, who will now play Demons in the final on January 24.
Dublin Inter got the perfect start with Mindaugas Tamausakas hitting a superb three-pointer in the opening minute.
Neptune looked shell shocked in the opening five minutes as Inter punished them at will to lead 17-5.
Surprisingly, Neptune looked nervous and with Mariuz Landos hurting them at the point Inter continued to harass them in defence.
Michael McGinn and Roy Downey were introduced but it made little difference as Inter led Neptune 27-11 entering the second quarter.
Neptune continued to struggle in defence and the home crowd looked stunned when a Mindaugas jumper gave Inter a 17-point lead in the 14th minute.
Roy Downey restored Neptune’s pride when he shot a monstrous three-pointer and when McLoughlin scored a lay-up on the next possession the home crowd sensed a revival.
Both sides played scrappy basketball in the closing minutes of the quarter but when Michael McGinn nailed a three-pointer with three minutes remaining the deficit was reduced to 43-33.
Downey did score a late free throw but Neptune were lucky to go in at the break trailing by only nine points as they had looked out of sorts at both ends of the floor.
Statkus gave Inter the perfect start when his banked shot found the target as Neptune continued to stutter.
Both sides played fast-flowing basketball for the remainder of the quarter but a late Cepliiasuskas Mazvydas basket ensured Inter led 58-46 entering the crucial final quarter.
Neptune rallied and with stalwart Ger Noonan going off injured the introduction of Michael McGinn helped the Cork side reduce the Inter lead to six points.
The atmosphere was electric as the home crowd willed their team on to victory, but when Ian McLoughlin slipped and allowed Mindaugas to score a lay-up in the 35th minute Inter’s lead was back out to eight points.
McLoughlin made up for his error with a stunning three on the next possession as Inter looked to be on meltdown.
In the dramatic closing minutes Neptune introduced Ger Noonan and the captain helped tie the game with 1.27 remaining on the clock.
Credit to Inter, however, as they held their nerve and deservedly booked their place in the decider.
Bord Gáis Neptune: G Walsh, B Kiely, M McGinn, I McLoughlin, D Lenihan, G Noonan, R Downey, J Kamara, D Cronin, D Dowling, M Kenny, D Townes, M Rudak.
Dublin Inter: S Aiden, M Cepliauskas, A Dimiciukas, A Statkmus, K Harrington, R Barry, R Eidukas, G Trakauskas, M Tamauauskas, L Glennon, M Landos, R Dimiciukas, L Jonaitis.
Referees: M Nazimek (Dublin), H Jones (Wales), J Walsh (Dublin).