The Haunting Blast is a powerful attack that Jack Skellington is able to use. It is a huge beam of energy that Jack can fire from his palms, which he used to kill Kermit in the Cute Mario Bros The Movie. Jack hasn't used the attack since then.
Cute Mario Bros The Movie
Jack first (and only) used the Haunting Blast in Cute Mario Bros The Movie, where he used it to finish off Kermit in the final battle. It appeared as a large beam of white energy (presumably spirit energy).
The Rise of Gonzo
In The Rise of Gonzo, The The Great Prophecy depicts Jack using the Haunting Blast to defeat Kermit, and is seen in a brief flashback. the attack (plus Kermit's death) is mentioned is part 2 by Gonzo and Kermit multiple times