How do you make a rhapthorne in dragon quest monsters joker?

To make a Rhapthorne in Dragon Quest Monsters: Joker, you need to fuse two specific monsters: a Rhapthorne I and a Rhapthorne II. First, ensure you have obtained both forms through leveling and breeding. Once you have them, go to the fusion menu and combine them to create Rhapthorne. Be sure to check their compatibility and ensure they meet any level requirements.