Crescent struck first with an intercept try from Jack Delaney who also converted the score in the 12th minute.
Christians did strike back with a try from Ronan O’Sullivan before the break and they then went ahead seven minutes into the second half when the fullback also converted a try from Finn MacFhlannchadha.
But the plot continued to thicken and Dara O’Shea grabbed the second try for Crescent to leave two points between the teams and with 15 to play.
It got better for Crescent when substitute Ben Davey danced his way over for a brilliant try that Delaney converted for a 19-14 advantage after 49 minutes.
But Christians responded to win another title with an injury time try from flanker O’Sullivan and the all-important conversion from Coomber.
G Coomber, M Buckley, H ORiordan (captain), L Daly, A Leahy, C Whooley, J Moylan, A O’Regan, S Rall, M Donnelly, R Kelleher, M McCarthy, F MacFhlannchadha, R O’Sullivan, C Lavin.
Replacements from: R Shalloe for Whooley (47, injured), J Moylan for O’Connor, B Kahn for MacFhlannchadha (both 50), P O’Hara for Buckley (56), B O’Donnell for O’Regan (61).
C Quilligan, G Kelly, T O’Sullivan, S Hurley, D O’Shea, J Delaney, J Connolly (captain), E O’Sullivan, J Skehan-Fitzgerald, J Cross, D Doyle, S Malone, B Scott, J McKeogh, D Rickard.
Replacements: B O’Sullivan for J Cross (37 injured) B Davey for Quilligan (38, injured).