The past tense of ‘cast’ is ‘cast’.
In English, some verbs are irregular and their past tense forms do not follow the standard pattern of adding ‘-ed’ to the base form. ‘Cast’ is one of those verbs. This means that when you refer to something that was cast in the past, you still use the word ‘cast’. For example, you might say, ‘He cast the fishing line yesterday.’ In this sentence, ‘cast’ indicates the action that took place in the past.