The correct spelling of the phrase "wast use" is in fact "was to use." The use of "wast" is an archaic form of the word "was," which was commonly used in Middle English. The IPA phonetic transcription for "was" is /wʌz/, while the phonetic transcription for "to" is /tu/. Therefore, the correct spelling of the phrase should be "was to use," which means something was meant or intended to be used.