Spartan easily won by 31 runs to qualify to meet Sports & Games YMPC.
Man-of-The-Match Mascoll, believed to be the oldest player in the match, was instrumental in Spartan reaching a workable total of 158 for seven in 40 overs after they opted to bat on a slow pitch.
Spartan were reeling at 73 for five in 23 overs until Mascoll and Dave Marshall combined to lift their spirits with a sixth-wicket partnership of 46.
With the score on 119, Marshall was leg-before to fast bowler Hendy Broomes, who had set back the scoring rate in his opening spell.
Mascoll struck 42 off 57 balls before he was run out on a second run by a throw from Shirley Clarke at mid-on to the wicket-keeper.
Spartan were off to a slow start, losing Ronnie Griffith through the run out route and, off the very next ball, Livingstone Puckerin was caught at first slip off Ryan Clarke.
Three balls later, Roy Alleyne offered Broomes an easy return to leave Spartan tottering at 19 for three in nine overs.
It took a mature innings of 36 by Mark Redman and valuable knocks by Hattian Graham and Dexter Toppin at the bottom of the innings to push along the score.
Carlton needed just over three runs per over to reach the target and were off to a flying start, scoring 50 runs without loss in ten overs.
Openers Chris King (29) and Jason Clarke gathered runs at will, after an allegation of ball tampering led the umpires to change the ball after six overs.
Clarke was extravagant in his strokeplay until leg-spinner Dave Marshall, in the 11th over, bowled him with a flighted delivery.
With the introduction of Marshall and off-spinner Hendy Springer, the innings went into decline from 54 without loss to 91 for seven.
Marshall captured the wicket of Wilbur Bruce, trapped leg before two balls after dismissing Clarke. He had survived a confident shout in the first delivery faced.
This sent panic into the Black Rock team, and Springer with four wickets for 17 runs, dented their hopes even more.
Mascoll was just as mean as the spinners, ending with two for 20, including the wicket of last man Ryan Clarke which sealed SpartanŐs victory.