Rashi, partially based on Eruvin 19a: Tafteh is Gehinom; anyone who is Mispateh (seduced by his Yetzer ha'Ra) falls there ¹ . It was prepared on he second day of creation, which has Esmol (yesterday), but not two days before it.

Pesachim 54a: Gehinom is one of the seven things that were created before the world.

Radak: Gehinom is prepared for Resha'im before they die. The Navi prophesized about them before the decree of their fall. When their bodies die, also their Nefashos will die, and will be in Gehinom.

Malbim: [After his defeat], Sancheriv planned to offer his sons to idolatry. People did so in Tofes (Yirmeyah 7:31). They built Bamos there to burn their children. Sancheriv prepared it for himself - his sons realized his intent, and killed him.

Rashi: For Sancheriv and his troops.

Radak: Sancheriv was haughty, and said 'I did with my strength and Chachmah.' Hashem made Gehinom deep and wide, so his entire camp could enter.

Malbim: Sancheriv made Tafteh deeper and wider to offer his sons there, even though there was already a woodpile and much wood to burn his sons there.

Rashi: This is an expression of a burning fire. A woodpile arranged to burn is called Medurah. Radak - it will burn the Nefashos of these Resha'im.

Rashi: It is the blowing of His Ru'ach.

Radak: It is the breath that comes out of His mouth, which is called Neshimah.

Malbim: It is Hashem's desire,

Radak: The fire will burn and not extinguish.

Malbim: The one who made the woodpile, he himself was burned, like a river [of sulfur] that extends and burns for a long distance.