I'm guessing it's the sort of thing you don't put into subtitles. The offer I am referring to is the one when Thranduil requests the moon stones from Erebor, in the King's throne room.
Here is the scene:
Thranduil: Some may imagine that a Noble quest is at hand. A Quest to reclaim a homeland and slay a dragon. I myself, suspect a more prosaic motive. Attempted burglary, or something of that ilk.
[he leans down to look at Thorin closely]
Thranduil: You have found a way in. You seek that which would bestow upon you the right to rule. A King's jewel. The Arkenstone. It is precious to you beyond measure, I understand that. There are gems in the mountain that I too desire. White gems of pure starlight. I offer you my help.
Thorin: I am listening.
Thranduil: I will let you go, if you but return what is mine.
Thorin: A favor for a favor.
Thranduil: You have my word. One King to another.
Thorin: I would not trust, Thranduil, the great King, to only his word. Till the end of all days be upon us!
[Thranduil looks visibly shocked at Thorin's words]
Thorin: You, lack all honor! I have seen how you treat your friends! We came to you once, starving, homeless; seeking your help. But you turned your back! You, turned away from the suffering of my people and the inferno that destroyed us!
[in his own language]
Thorin: May you die in dragon fire!
Thranduil: Do not talk to me of dragon fire! I know it's wrath and ruin. I have faced the great serpents of the North.
[suddenly one side of Thranduil's face becomes distorted, showing signs of being once burnt, then as he steps back his face returns to it's normal state]
Thranduil: I warned your grandfather of what his greed would summon, but he would not listen.
[Thranduil walks up the steps to his throne]
Thranduil: You are just like him.
[he motions for his guards to grab hold of Thorin who struggles as they hold him and take him away]
Thranduil: Stay here if you will, and rot. A hundred years is a mere blink in a life of an Elf. I'm patient. I can wait.
Balin: Did he offer you a deal?
Thorin: He did. I told him he could go ishkh khakfe andu null. Him and all his kin!
Balin: Well, that's that then. The deal was our only hope.
Both passages from here.
Was this phrase ([in his own language] above) and his one to Balin (ishkh khakfe andu null) in the book. What did they say?