A.T. Robertson Commentary John 18:32

"that the word of Jesus might be fulfilled, which he spake, signifying by what manner of death he should die." — John 18:32 (ASV)

By what manner of death (ποιω θανατω). Instrumental case of the qualitative interrogative ποιος in an indirect question, the very idiom used in Joh 12:32 concerning the Cross and here treated as prophecy (Scripture) with ινα πληρωθη like the saying of Jesus in verse 9 which see.