I like the NRSV of these verses. Verse 3 and 4 of Chapter 14 put the whole thing into its correct context perfectly.
Isa 14:3 (NRSV) When the Lord has given you rest from your pain and turmoil and the hard service with which you were made to serve, 4 you will take up this taunt against the King of Babylon.
Then follows.......
"How the oppressor has ceased,
the insolent fury ceased!
5The LORD has broken the staff of the wicked,
the scepter of rulers,
6 that struck the peoples in wrath
with unceasing blows,
that ruled the nations in anger
with unrelenting persecution.
7The whole earth is at rest and quiet;
they break forth into singing.
8 The cypresses rejoice at you,
the cedars of Lebanon, saying,
'Since you were laid low,
no woodcutter comes up against us.'
9 Sheol beneath is stirred up
to meet you when you come;
it rouses the shades to greet you,
all who were leaders of the earth;
it raises from their thrones
all who were kings of the nations.
10 All of them will answer
and say to you:
'You too have become as weak as we!
You have become like us!'
11Your pomp is brought down to Sheol,
the sound of your harps;
maggots are laid as a bed beneath you,
and worms are your covers.
12"How you are fallen from heaven,
O Day Star, son of Dawn!
How you are cut down to the ground,
you who laid the nations low!
13You said in your heart,
'I will ascend to heaven;
above the stars of God
I will set my throne on high;
I will sit on the mount of assembly
in the far reaches of the north;
14I will ascend above the heights of the clouds;
I will make myself like the Most High.'
15 But you are brought down to Sheol,
to the far reaches of the pit.
16Those who see you will stare at you
and ponder over you:
'Is this the man who made the earth tremble,
who shook kingdoms,
17who made the world like a desert
and overthrew its cities,
who did not let his prisoners go home?'
18All the kings of the nations lie in glory,
each in his own tomb;
19but you are cast out, away from your grave,
like a loathed branch,
clothed with the slain, those pierced by the sword,
who go down to the stones of the pit,
like a dead body trampled underfoot.
20You will not be joined with them in burial,
because you have destroyed your land,
you have slain your people.
These verses clearly pertain to the King of Babylon, not Satan. They are all part of the same proverb, verse 12 is not separated from the previous verses.
NIV has verse 3 and 4 almost the same. New Life has it 3 When the Lord gives you rest from your pain and trouble and the hard work which you were made to do, 4 you will speak against the king of Babylon, and say Youngs literal has it 3And it hath come to pass, In the day of Jehovah's giving rest to thee, From thy grief, and from thy trouble, And from the sharp bondage, That hath been served upon thee,
4That thou hast taken up this simile Concerning the king of Babylon, and said, How hath the exactor ceased, NASV has it 3 And it shall come to pass in the day that Jehovah shall give thee rest from thy sorrow, and from thy trouble, and from the hard service wherein thou wast made to serve,
4 that thou shalt take up this parable against the king of Babylon,
And many more versions have verse 3 and 4 clearly preceeding this proverb against the King of Babylon. Amazing how Christians that believe the fall of satan from heaven nonesense use verse 12 of Chapter 14 as a "proof" scripture, and never see verses 3 and 4.