Ah, the ol' meteor hit. There isn't actually a tutorial, but there is a simple breakdown of the effect on the VisionLab gallery page
. Under compositing, check out the Meteor Impact video. Still, that particular effect does get asked about fairly often. It nicely combines a number of techniques, including the following:
The stormy sky is created with the particle engine, used to create some fairly quickly roiling clouds.
The flaming meteor itself is several layers of stock footage combined. Additional stock footage is used for the explosions which occur on impact.
The entire frame is shaken with the animation controls to add to the intensity of the impact.
Grading is used to create the scorch marks left on the ground as the meteor burns out.
That covers the important bits, I think, and a general knowledge of VisionLab should make those relatively easy to implement, once you have a plan in place. If any specific part of that confuses you, or you'd like further explanation, let us know, but its fairly straightforward.