Complex sentence: Initially, Marcel Vercoutere, a special effects man who previously worked with the director on "The Exorcist" was to be responsible for the explosion, however it did not achieve the required effect and barely damaged the tree.
Split into simpler sentences: Initially, Marcel Vercoutere, a special effects man who previously worked with the director on "The Exorcist", was to be responsible for the explosion. However, it did not achieve the required effect and barely damaged the tree.