Based on the search results, there is no information on what the Puppet Master is weak to in Prodigy. However, there are several tips on how to defeat the Puppet Master, such as using high health pets that do high physical damage and have a lot of health, equipping the best equipment available, and using the highest damage spells available. Additionally, it is recommended to use Astral spells on the Puppet Master and to have pets with high health so that they can survive the Puppet Masters big attack.