It was a brutal ending for the Ben Bulben side who contributed richly to an epic encounter.
St Marys young goalkeeper Jack Teape was the hero of the day, bringing the game to a penalty shoot out by converting a 45m free with literally the last kick of the game and then saving three Drumcliffe penalties to seal the victory.
The tight ending was a fitting finale to a game where there was never much between the teams as it ebbed and flowed with a string of excellent scores from both sides.
Drumcliffe, who have never won a senior championship were first on the scoreboard with an Eoghan Smith free in the first minute.
This was quickly cancelled out by a fine Stephen Coen point to get St Mary's on their way.
Teape made his first contribution to the scoreboard with a free from distance after a heavy collision between Emlyn Mulligan and Neil Ewing in the centre of the park.
Smith and Coen then exchanged two excellent points - the Drumcliffe man on the turn from over 45 metres when it looked like the defence had closed down his options and Coen from a tight angle after a sumptuous cross field ball by Mulligan
Smith's third point on seven minutes levelled things.
There followed a period where both sides sought to impose their pattern on the game through possession with St Marys getting the better of the opportunities but without adding to the scoreboard.
Drumcliffe Rosses Point had posted Cian Lally on the edge of the square and he burst into the game with two points, the first a fisted effort and the second the conversion of a an excellent mark to give his side a two point lead.
Smith extended the Drumcliffe Rosses Point lead to three, 6-3, as the game entered the last five minutes of the first half
St Marys wing back Ryan Madden got up to pull one back but another Smith free for a David Phillips foul on Lally restored the three point advantage.
Rooney and Michael Munnelly added two further points for St Mary's while Smith again and Neil Ewing with a beautiful angled shot from the right added points for Drumcliffe before Teape had the last word of an excellent first half with a free from outside the '45 to leave the score at 9- 7 in favour of Drumcliffe Rosses Point at the half time break.
The opening ten minutes of the second half continued the pattern with points from Coen, Paul Kilcoyne and Gerard O'Kelly-Lynch for St Mary's matched by Danny Cronin, Smith and a wonderful Ewing effort off the outside of the right boot from wide on the left to bring the scores to 12 - 10 in favour of Drumcliffe.
That all changed in a burst of three minutes as St Mary's smashed in two goals to turn the game on its head.
Firstly Gerard O'Kelly-Lynch surged forward from the half back line to create an opening for Michael Munnelly to crash home.
Stephen Coen added a point before Scott Lynch capitalised on hesitancy in the Drumcliffe goalmouth to raise a second green flag and in three minutes the Oxfield Park side had gone from protecting a two point lead to chasing a five point deficit.
They were up for the chase however and after a exchange of points between Smith and Mulligan, substitute Niall Colleary got inside the St Mary's defence to crash home a goal, quickly followed by another Lally point to leave just one point between the sides as the game entered its final ten minutes.
St Mary's hit back though with two Stephen Coen points, one a free, to extend the gap to three but those were to be their final scores of normal time as tenacious Drumcliffe defending, led by Ross Chambers and Lee Cummins kept them at bay and set up opportunities for Smith, an inspirational point on the run from captain Sean Power and finally Smith again from a free in added time to tie the game at full time at 1-17 to 2-14, leading to extra time.
St Mary's Nathan Rooney was first to strike in extra time with two points that were cancelled out by Colleary and Paul Logan for Drumcliffe to leave the sides still deadlocked at half time in extra time.
Drumcliffe were hampered in the second half of extra time as top scorer Eoghan Smith was forced to retire injured but substitute Eoin Gaughan put them ahead again, 1-20 to 2-16, with three minutes to play.
With excitement at fever pitch throughout the ground, and tired bodies on the field, both sides had opportunities to add to their tally but with the extra time slipping into added time, a foul called just outside the Drumcliffe 45m saw Teape called on again and he put his third point of the day plum between the posts to bring the game to penalties.
In the shoot out, Drumcliffe went first and St Marys got an immediate advantage when Teape saved from Gaughan, giving Rooney the chance to put the Ballydougan side one up.
Logan then netted for Drumcliffe and Munnelly for St Mary's.
Teape saved Drumcliffe's third from Colleary before Mulligan gave St Mary's a 3-1 lead.
That left Drumcliffe needing to score all of their remaining kicks to bring the contest to sudden death. Teape settled the matter though with his third save, this time from Ciaran Smith, and so it is St Marys who will contest this year's final to see if they can regain the Owen B Hunt Cup that they last won in 2015
St Marys: Jack Teape (0-3); Ryan Feehily, David Phillips, Fionn O'Hehir; Gerard O'Kelly Lynch (0-1), Luke Nicholson, Ryan Madden (0-1); Pau Kilcoyne (0-1), Tony O'Kelly Lynch; Michael Munnelly (1-1), Emlyn Mulligan (0-1), Patrick Maher (0-1); Stephen Coen (0-5, 1f) , Nathan Rooney (0-3 2f) Scott Lynch (1-0) Subs; J Martyn for Nicolson 23 (inj), Jay Cox, Stephen Henry, Sean Clifford
Drumcliffe-Rosses Point; Paul Durcan; Ross Chambers; John McGowan; Ciaran O'Reilly; Cian McBride; Lee Cummins, Stephen Regan; Sean Power (0-1), Ciaran Smith; Neil Ewing (0-2), Eoghan Smith (0-9, 5f), James Donlon; Cian Oates, Cian Lally (0-4), Danny Cronin (0-1) Subs: Jude McGarry, Niall Collery (1-1), Eoin Gaughan (0-1), Paul Logan (0-1), Paul O'Brien, Kevin Dufficey