At midnight Jehovah killed every firstborn male in Egypt from the firstborn son of Pharaoh who ruled the land to the firstborn son of the prisoner in jail, and also every firstborn animal.

I will send an epidemic and destroy them. I will make you the father of a nation that is larger and more powerful than they are!

Moses said to Aaron: Take your incense burner, put burning coals from the altar and incense in it, and go quickly into the congregation to make peace with Jehovah for the people. Jehovah shows his anger! A plague has started.

He cleared a path for his anger. He did not spare them from death. He let the plague take their lives.

Jehovah (YHWH) is a zealous God requiring exclusive devotion (tolerates no rivals). Jehovah takes vengeance (punishment) against his adversaries. He reserves (maintains) wrath (indignation) (displeasure) against his enemies.

And

Then the earth shook and quaked. Even the foundations of the mountains trembled. They shook violently because he was angry.

Burning coals

They will be wasted by famine, and consumed by plague and bitter destruction. I will send teeth of wild animals on them, with the venom of crawling things (reptiles) of the dust.

General references

He covers the face of the full moon, and spreads his cloud over it.

Its breath kindles coals, and a flame comes out of its mouth.

A fire goes before him and burns up his enemies round about.