The phrase "wast on" is spelled with the phonetic symbols /wɑːst/ for the word "waste" and /ɒn/ for the word "on". The sound for "w" is represented by the letter "W" and its IPA symbol is /w/. The vowel sound in "waste" is represented by the letter "a" and its IPA symbol is /ɑː/. The sound for "n" is represented by the letter "n" and its IPA symbol is /n/. Therefore, the correct pronunciation of this phrase is "waste on".