The combination of two or more metaphors is called

The combination of two or more metaphors is called mixed metaphor.
Metaphors are figures of speech that use language to compare two unrelated things, usually for the purpose of creating vivid descriptions or conveying a particular meaning. When multiple metaphors are brought together in a single sentence or phrase, it creates a mixed metaphor.
Imagine if someone said, "He's as sharp as a knife, but also a shining star." In this example, the person is using two different metaphors: one comparing someone to a sharp knife and another comparing them to a shining star. However, when these two metaphors are combined, it creates a mixed metaphor.
Mixed metaphors can sometimes create confusion or make the intended meaning unclear. It is generally more effective to stick to one metaphor at a time to ensure clarity and coherence in communication.