The second week of testimony in the Diddy trial is in the books … and prosecutors continued to try and prove their racketeering case against Diddy, with the help of Kid Cudi.

Cudi took the stand Thursday and told the jury about a couple incidents from his 2011-12 love triangle with Cassie and Diddy … including a break-in at his home and a Molotov cocktail dropped in his Porsche.

Kid Cudi said Diddy broke into his home and rummaged through his Christmas gifts after finding out he was dating Cassie … and he said he was convinced Diddy had something to do with his Porsche getting torched too.

A celebrity makeup artist also took the stand and she testified she saw Cassie with injuries to her face after a heated exchange with Diddy in a hotel room following a 2010 Grammys party at Prince‘s house.

Prosecutors also called a hotel manager from a swanky spot in L.A. to testify about Diddy as a guest … and the hotel kept notes that Diddy liked the room hot and to deep clean his room because there was always candle wax and baby oil damage.

Cudi’s testimony was pretty interesting but the best shot prosecutors might have of nailing Diddy on a RICO charge is Suge Knight … who told us Diddy would absolutely have used guns if he found Suge at Mel’s Drive-In … a callback to a story previously told this week in court.

Suge kinda ties this whole criminal organization thing together … but we talked to him from prison, and the prosecution did not call him as a witness.