D&D adventure

the giant creature seems a Little bit to scary so you run to the nearest set of stairs. The creature chases you down screaming in his blehblooblahblahblah language, you go to the nearest room and try to shut the door behind you, but its too strong, it gets through and shoves you to the ground you try to run but you cant .All of the sudden behind you is a blue dragon that electrocutes you to a crisp.
you thought, "where in the heck did that come from?"