Kog'maw -> Cho'gath Respect your elders? In the void we eat our elders.

Jarvan -> Swain: A thousand times would not be enough. But I'll settle for this.
Jarvan -> Urgot: Garen will find this amusing.
Jarvan -> Gangplank: Oranges won't save you from this.
Jarvan -> Olaf: And they said it was impossible to contain you.

Gangplank -> Jarvan: Even princes can be at the mercy of pirates.

There should be a burpin' sound whenever I kill a Yordle! They got in mah belleh after all! *pats belleh*

Skarner -> Kennen: It's super effective! (you know, cause of the whole Pokemon thing)

Yi -> Wukong: You still have much to learn
Yi -> Heimerdinger: Thanks again for the Seven Lenses
Yi -> Singed: Suffer for your crimes
Yi -> Rammus: Not fast enough
Yi -> Any other champion: Get dunked! (not in character, true, but a tribute to the guide)
Yi -> Any other champion: Wuju improve your skills?

Nasus-> janna: you couldn't weather the storm

Nasus-> zilean: (used wither) none can conquer time

Nasus -> any of the ninja trio: ...balance

Nasus-> renekton: rest, brother

Nasus-> kayle/morgana: I warned you where you tread

Xerath to Ezreal: "THE POWERS OF INFINITE MAGIC DOES NOT BELONG TO AN INFERIOR MORTAL!"

Ezreal to Xerath: What a shame, was planning on putting this coffin in the next exhibit

Ryze to Xerath: You will never be able to witness the secrets of this scroll. I can sense that you want it back

Xerath to Ryze: SOON THE POWERS WITHIN THE SCROLL WILL FREE ME FROM THIS CURSED PRISON!

Rammus to Talon: Hehe, a knife on my back! (A joke on how he can soak up AD casters a lot better than Autoattackers)

Rumble to any Yordle: Who's the meanest, baddest yordle in town? That's me! Size means everything!

Teemo to Tristana: You need more precision Tristana, failing that just the dose of poison.

Tristana to Teemo: Nice shooting match Teemo, but you make a better spotter.

"There is no Evolution for you"

- Viktor, the Machine Herald

Olaf -> Anyone: Sorry, I had to "axe" you a question.