Could someone explain to me the function of the particle と in this case?
ちりと化すぞ
ありがとうございます。
「と」in this case marks what the subject is turning or changing into. For example,「死体は塵{ちり}と化した」would mean "the body turned to dust".
It is similar to particle に in this use, and in fact could be replaced by に. You can find an explanation of the difference between the two here.