κατακαίω

Matthew 3:12 κατακαύσει He will burn up

His winnowing fork is in His hand to clear His threshing floor and to gather His wheat into the barn; but He will burn up the chaff with unquenchable fire.”

Here: Future, 'he will burn up'. The prefix kata- makes the burning total, so the chaff is consumed and nothing is left.

Matthew 13:30 κατακαῦσαι to burn

Let both grow together until the harvest. At that time I will tell the harvesters: First collect the weeds and tie them in bundles to be burned; then gather the wheat into my barn.’”

Here: The prefix kata- adds 'completely': burned down to nothing. In 13:40-42 this becomes the 'furnace of fire'.

Matthew 13:40 κατακαίεται, is burned up,

As the weeds are collected and burned in the fire, so will it be at the end of the age.

Luke 3:17 κατακαύσει He will burn up

His winnowing fork is in His hand to clear His threshing floor and to gather the wheat into His barn; but He will burn up the chaff with unquenchable fire.”

Here: Future tense: he will burn it. The prefix kata- makes it "burn down, burn up completely." The verb changes here from the purpose infinitives to a flat statement of what will happen.

Acts 19:19 κατέκαιον were burning [them]

And a number of those who had practiced magic arts brought their books and burned them in front of everyone. When the value of the books was calculated, the total came to fifty thousand drachmas.

1 Corinthians 3:15 κατακαήσεται, will be burned up,

If it is burned up, he will suffer loss. He himself will be saved, but only as if through the flames.

Hebrews 13:11 κατακαίεται are burned

Although the high priest brings the blood of animals into the Holy Place as a sacrifice for sin, the bodies are burned outside the camp.

Here: 'Are burned up', destroyed completely and not eaten. The singular verb with a plural neuter subject is normal Greek. Like 'is carried in', it states the rule the law lays down.

Revelation 8:7 κατεκάη· κατεκάη, κατεκάη.¶ was burned up;, were burned up,, was burned up.

Then the first angel sounded his trumpet, and hail and fire mixed with blood were hurled down upon the earth. A third of the earth was burned up, along with a third of the trees and all the green grass.

Here: 'Was burned down / burned up'. The prefix κατα- makes it complete destruction by fire, not scorching. The verb ends each of the three clauses, which gives the verse a hammering rhythm.

Revelation 17:16 κατακαύσουσιν they will burn

And the ten horns and the beast that you saw will hate the prostitute. They will leave her desolate and naked, and they will eat her flesh and burn her with fire.

Here: The prefix kata- makes the verb intensive: burn down, burn to nothing. This is how a conquered city was destroyed (18:8, 9, 18: the smoke of her burning).

Revelation 18:8 κατακαυθήσεται, she will be burned up,

Therefore her plagues will come in one day—death and grief and famine—and she will be consumed by fire, for mighty is the Lord God who judges her.”

Here: The prefix κατα- makes it complete: 'burned down, burned up'. The passive voice leaves the one doing it unnamed. Revelation 17:16–17 says the beast and ten horns do it, while God put it in their hearts.