Part1:
Zetsu: Just like Amaterasu, it can't be dodged... What kind of jutsu in the world is it?!
Lightnings crossing the sky.
Zetsu1: Now I got it... He threw that katon just for this purpose!
Zetsu2: What do you mean?
Zetsu1: He wasn't really aiming at Itachi... He aimed purposedly at the sky so that the sudden heating would result in strong currents... In other words, those clouds are now filled with electricity...
Even if he's out of chakra now he's preparing to perform a raiton jutsu by using the power stored in the clouds... Anyway this is quite different from elemental manipulation...
Part2:
Sasuke: This jutsu has lightning descend from the heavens. I'll just be leading it straight to you.
Zetsu: I knew it. If that's the case, there's no way he'll get away. Lightning bolts hit in a thousandth of a second, faster than the sound!
Sasuke: The name of the technique is "Kirin".
Sasuke: Scatter along with the thunder!
Itachi is hit! He collapses.
Zetsu: Is Itachi dead?
Sasuke; It's over!
Sasuke deactivates the Sharingan and sits down
Itachi: Is this the death you hoped to reproduce for me?
Sasuke: !?
Itachi rises!
Sasuke: ****!
Sasuke turns level 2. Itachi has enclosed himself by what seems to be armor
Itachi: If it wasn't for this, you would have been able to beat me. Sasuke, you truly have become stronger. This time I'll show you my final ace...Susanoo.
A jutsu used against a chakra-less Sasuke? Next chapter is the conclusion!