Places fire charges in a dispenser then launching them causes it to shoot out dragon breath instead. In survival mode, it will gradually do damage to you until your are killed as the ender dragon would do.

How to recreate glitch:
1) Get a dispenser, fire charge, and something to power the dispenser like a level
2) put fire charge in dispenser
3) use the lever (or something else) and watch the dragon breath come out

What should happen is that the dispenser should shoot out a fire charge, not a dragon breath.