I don't quite understand what you mean by "What comes after the lake of fire?".
I'll try to answer the question though.
...the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever. - Revelation 20:10
...death and hell were cast into the lake of fire. This is the second death. - Revelation 20:14
...whosoever was not found written in the book of life was cast into the lake of fire. - Revelation 20:15
I hope you can appreciate that the lake of fire - the second death is a state, just as death is a state. It represents a final state of not-existence. So that there is no return for anything going there.
This would mean that the Devil; the beast; the false prophet; death; man's burial place (grave - Hades); whosoever was not found written in the book of life, are all gone permanently - forever.
After these are permanently gotten rid of, then
comes the end, when he [Christ] delivers the kingdom to God the Father, when he [Christ] puts an end to all rule and all authority and power. For he [Christ] must reign till he [Christ] has put all enemies under His feet. The last enemy
that will be destroyed
is death. For “He [God] has put all things under His [Christ's] feet.” But when He says “all things are put under
Him,”
it is evident that He [God] who put all things under Him is excepted. Now when
all things are made subject to Him, then the Son Himself will also be subject to Him who put all things under Him, that God may be all in all. - 1 Corinthians 15:24-28
Recall that the seed was to crush the head of the serpent - Satan the Devil Genesis 3:15
That seed is Christ and the 144,000 heirs of the kingdom - Galatians 3:16,
29
They anticipates this.
I hope that was an answer to your question.
Basically, that is the end of death, and the one who caused it - Hebrews 2:14, and God's purpose would have been accomplished.