$category = 'Insanity';

$dom = new DOMdocument( );

$success = $dom->load( 'http://circusoflamia.blogg.se/index.rss' );
if( !$success )
        die( 'failed to load url' );

$elements = $dom->getElementsByTagName( 'item' );
$items = array( );

foreach( $elements as $element ){
        $item = array( );

        if( $element->getElementsByTagName( 'category' )->item( 0 ) == $category ){
                foreach( $element->childNodes as $node )
                                $item[ $node->nodeName ] = $node->nodeValue;
             
                array_push( $items, $item );
        }
}

die( print_r( $items ) );