Sean “Diddy” Combs is on a heater, at least when it comes to tackling the mountain of lawsuits he’s facing … and now former “Making The Band” singer Sara Rivers is finding out firsthand what kind of roll he’s on.

According to new legal docs, obtained by TMZ, a judge just threw out 20 claims Sara made against Diddy in her lawsuit. They were dismissed with prejudice, meaning they cannot be filed again.

Among the claims dismissed … racketeering, assault and battery, forced labor, sexual harassment and false imprisonment.

The only claim remaining against Diddy is one under the Gender-Motivated Violence Protection Act … and the judge says he’s waiting for a ruling from a higher court to determine whether to dismiss this claim as well.

We broke the story … Sara sued Diddy back in February, claiming Diddy subjected her to hostile and inhumane treatment on the reality TV show, “Making the Band 2.”

The suit, filed by attorney Ariel Mitchell on behalf of Rivers, cited the infamous “cheesecake” from ‘MTB2’ where she and the rest of Da Band had to walk several blocks to get Diddy a sweet treat as one of the numerous incidents of abuse.

Sara also complained of being forced to sleep in an open bay with 4 other males despite the fact she was married at the time, and said she was threatened with being ousted if she didn’t comply.

She also alleged Diddy acted maliciously and recklessly with her career by publicly dismantling the group while pocketing most of her show money … and she claimed Diddy sexually harassed and assaulted her, claiming he once backed her into a corner and blocked her from moving while running his hand across her breasts.

The lawsuit also named as defendants MTV, Viacom, UMG and several ex-Bad Boy employees who had a profile on the series at the time … including Diddy’s mother, Janice, and ex-assistant Fonzworth Bentley. In total, 21 claims were dismissed.

Mitchell tells TMZ … “We plan to appeal — and we look forward to more litigation specifically against Mr. Combs.”