# Upgrade heroes Each hero needs to raise stars to become stronger. When a hero is upgraded, the internal stats and skill stats (Skill) will increase. The upgrading mechanism is explained as follows: * From 1 star to 2 stars: combine three heroes of the same kind or use your hero and an 'Upgrade Gem' to upgrade the hero * From 2 stars to 3 stars: combine three 2-star heroes of the same kind --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://medium-sp.gitbook.io/space-marvel/gameplay/heroes/upgrade-heroes.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.