Dumerc, who moved to UMMC from Bourges during the summer, was the club's biggest signing but missed the first six EuroLeague games through injury.
She is a pivotal player for a UMMC side that is looking to end Spartak Moscow Region's run of three straight titles in the competition.
UMMC never trailed in Wednesday's game though they did not begin to take command until late in the first quarter after Ilisaine David's jump shot had trimmed the home side's advantage to 9-7.
Starting with a Maria Stepanova free-throw, the Russian team went on a 16-2 run bridging the first and second quarters to lead 25-9.
In that spurt, Dumerc scored five points for the Russian team.
By half-time, UMMC were on top 39-21 and they lowered the boom in the third quarter, outscoring the visitors 26-7 for a 65-28 lead.
Gundars Vetra's side cruised the rest of the way as it improved to 6-1 in Group A.
Cras saw their four-game winning streak come to an end and are now 4-3.
Dumerc's fellow France international Sandrine Gruda had 16 points to lead all scorers with Stepanova contributing 11.
Agnieszka Bibrzycka and Ann Wauters poured in 10 points apiece for UMMC.
The Italians, who were out-rebounded 46-32, got 12 points from David.
UMMC were 24 of 50 (48%) inside the arc compared to Taranto's 13 of 44 (29.5%).