Manual:Hooks/ParserBeforeStrip

Details
$text will hold the text for the page. To change the page text, modify this value. E.g. to add the phrase "The mighty oracle gives forth this proclamation: " to the front of the page text, you would use the following code:

$text = "The mighty oracle gives forth this proclamation: ". $text;

Note that this hook is generally called more than one time during page rendering. Therefore, you may want to use code such as this to ensure that it only runs once: