p-er-1
The plagues of Egypt provide clues

    "And the third angel poured out his vial upon the rivers and fountains of waters; and they became blood. . . . thou hast given them blood to drink; for they are worthy." (Rev. 16:4, 6)

Why are the seven plagues called plagues?
   When we think of the seven last plagues, we remember the plagues of Egypt. The word is translated from the Greek, plague, (pronounced, play-gay) which also means wound or blow or disaster. Here, for example, is Moses' account of the first plague to fall on Egypt. It compares to the second plague of Revelation.

   "Get thee unto Pharaoh in the morning; lo, he goeth out unto the water [apparently to worship]; and thou shalt stand by the river's brink. . . . And thou shalt say unto him, The LORD God of the Hebrews hath sent me unto thee, saying, Let my people go, that they may serve me in the wilderness: and, behold, hitherto thou wouldest not hear. Thus saith the LORD, In this thou shalt know that I am the LORD: behold, I will smite with the rod that is in mine hand upon the waters which are in the river, and they shall be turned to blood. And the fish that is in the river shall die, and the river shall stink; and the Egyptians shall lothe to drink of the water of the river." (Ex. 7:15-18)

What was the issue in the contest with Pharaoh?
   We usually think of slavery as the problem God solved in sending the ten plagues on Egypt, and this is certainly correct. But the bigger issue, the one that fueled the slavery problem, was worship of the true God. The Egyptians worshiped the sun, the river, and other things. They also had a goddess of fertility, Isis, similar to Diana of the Ephesians and the Anglo-Saxon goddess Eostre (which was picked up by Christian leaders as Easter in their eagerness to develop a religion pleasing to the pagans). Image from Corel.
   The Hebrews in Egypt did not have religious liberty. Moses was not free to teach them what they had, over generations, forgotten.
   "And afterward Moses and Aaron went in, and told Pharaoh, Thus saith the LORD God of Israel, Let my people go, that they may hold a feast unto me in the wilderness. And Pharaoh said, Who is the LORD, that I should obey his voice to let Israel go? I know not the LORD, neither will I let Israel go." (Ex. 5:1, 2)

 

p-er-2
How were the plagues the last?

  "And I saw another sign in heaven, great and marvelous, seven angels having the seven last plagues; for in them is filled up the wrath of God." (Rev. 15:1).

   Why are these the "last" plagues? In our verse, the wrath of God is complete. The reading "filled up" may be like the plague bowls (of vials) being filled. However, the primary reason may be seen in a comparison with the plagues of Egypt. We recall that there were 10. Do they match the last seven of those in Egypt? Apparently not as far as what was hurt by the corresponding plagues.
 

What is different about the first three plagues on Egypt?
    The Egyptian magicians were able to imitate the first two plagues. At that point, God set a limit to the satanic miracles. "And the magicians did so [tried to imitate] with their enchantments to bring forth lice, but they could not: so there were lice upon man, and upon beast. Then the magicians said unto Pharaoh, This is the finger of God: and Pharaoh's heart was hardened, and he hearkened not unto them; as the LORD had said." (Ex. 8: 18, 19)
   In the description of the next plague, we read, "And I will sever [set apart] in that day [that Pharaoh refuses] the land of Goshen, in which my people dwell, that no swarms of flies shall be there; to the end thou mayest know that I am the LORD in the midst of the earth. And I will put a division between my people and thy people: to morrow shall this sign be."  (Ex. 8:22, 23)
   So from the time following the third plague when the superiority of the true God was clear to all, it was evident that it was fair for God to protect those who believed in Him. This will be the same situation during the seven last plagues.
   Praise God for His justice and His mercy!

Three end-time plagues
   In the sounding of the sixth trumpet, we find plagues of fire from horses, smoke, and brimstone. I had considered that they correspond to the first three of Egypt but for several reasons, they don't fit: My primary understanding of the sixth trumpet is that it pictures trouble for the wicked, with the righteous protected as they are under the fifth trumpet ch8table. Also, the seven last plagues come in different symbols and location.
   You might discover a relationship. I conclude that they are the seven last plagues because, like the final seven plagues of Egypt, they will be only the wicked.

p-er-3
Did God make Pharaoh sin?

   We already know the answer, but it's worth a moment of reflection to understand why. "Let no man say when he is tempted, I am tempted of God: for God cannot be tempted with evil, neither tempteth he any man:" (James 1:13).
   In the verse quoted in the previous module (link), God is not seen as involved. Pharaoh stiffened his resistance when he saw that the Hebrews' God had superior power. Elsewhere we see Pharaoh hardening his own heart, ex0815. 1sa0606 agrees. Because God is ultimately in control, He may be said to cause things He permits.
   He could have stopped the wicked king before allowing the waters to return to drown him with his army in the Red Sea. Why didn't He? Before the situation became totally clear, His justice could have been questioned and the people of that time would not have fully understood the terrible consequences of rebellion against God. Also, the story would not have been clear for us today.
   Soon, the hand of God will again allow uncontrolled evil, like the waters of the Red Sea, to do their natural work. In Revelation we see that God will allow the four winds of strife to blow in unrestrained fury. That will be the time of the seven last plagues. Does God care? ". . . As I live, saith the Lord GOD, I have no pleasure in the death of the wicked; but that the wicked turn from his way and live: turn ye, turn ye from your evil ways; for why will ye die, O house of Israel?" (Ezek. 33:11).

   May God help each of us to be faithful. We may praise Him for His justice as well as for His mercy.