Xmen animated series question?

There was this episode where the xmen were fighting Mr. Sinister, Magneto was in it. Magneto and Xavier were stuck on a dinosaur island for a while. At the end, they are in this castle fighting Mr. Sinster. That mutant he brainwashed is there also, the one they thought the sentinels killed. At the end, he teams up with Cyclops and blows up Mr. Sinister and Jean ters his pieces everywhere. Does anybody know the name of that episode, I heard the series was finally coming to dvd and I was hoping that the episode was on the dvd's. Can anyone help?