# Rule of Cosmos The rule of the Cosmos ensures, only one of each champion, artifact, realm, and holding card can be in play at a time. This means that a player's opponent cannot have the same card in their pool or battle. Same cards, even if they are upgraded, cannot be played. Whether a realm is razed or not, it remains in play, preventing other players from playing the same realm into their formation. --- # 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://whitepaper.spellfire.com/spellfire-whitepaper/spellfires-gameplay/rule-of-cosmos.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.