Heretic leader glitch

The Heretic Leader Glitch will allow you to meet and kill the Heretic Leader on the Arbiter one level before you're supposed to.

WARNING!: Do not do this if you are trying to beat the game, because the Phantom that comes to support you will sit there and keep on shooting at the Heretic Leader, and it will not trigger any enemies or the door to open at the end of the level.

Walkthrough
Go onto the level The Arbiter, and go through it, keeping a charged Energy Sword with you the entire time. Eventually, you will come to a room, where you can see the Heretic Leader out on a Banshee Launchpad through a sheet of ornate glass. The reticule will turn red if you get close and move it over him. Get out your Energy Sword, and start attempting to lunge at the Heretic Leader through the glass. Crouch, jump, and crouch-jump, tapping the right trigger the whole time. It may take a few tries, but eventually the Arbiter will lunge, going straight through the glass at the Leader. Quickly grab his Banshee before he can pilot it, pick off his men, and you will have an inanimate Heretic Leader model. He is completely invincible, though you can kill him by knocking him off the ledge onto the pipeline below it. He screams the same way as when he is killed on the next level, The Oracle.

He will also die if you hijack his Heretic Banshee, but if you go anywhere down towards where he fell you will die. You will then revert to your last checkpoint.