Why did Hashem make His voice heard?
Rashi: When His angel came [to kill Machaneh Ashur], he came with the sound of thunder. It befuddled them, and their Neshamos departed.
Malbim: It was to scare Machaneh Ashur.
What is the meaning of "v'Nachas Zero'o"?
Rashi: This is not an expression of No'ach (rest), rather, Noches (bringing down), like "va'Yanach b'Chol Gevul Egypt" (Shemos 10:14). The descent of His Gevurah will be seen in "Lahav Esh"; the multitudes of Sancheriv were burned.
Radak: The Targum of "va'Yered" (Bereishis 12:10) is v'Nachas. Hashem will bring His arm, i.e. His Makah, on them.
Malbim: Before He struck them, He showed them His arm descending, to scare them.
Why does it say "v'Lahav Esh Ochelah"?
Radak: This is like Chazal said (Sanhedrin 94a), the Neshamah was burned, and the body was intact, like I explained (Melachim II, 19:35).
What is "Nefetz"?
Rashi: It is an expression of greater breakage. Radak - it is as if shattering lightning bolts and a flood of rain and hailstones descended. So they will be wiped out quickly.
What is "Zerem"?
Rashi: It is a flow of flooding rain.
