Your Champion dies to another specific Champion. Post up special "death dialogue".
It's hard to describe via the title, so I'll post some examples.
killed by
"Diana... why..."
killed by
"Fat... Hands..."
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"N-Not... like... this..."
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"Traitor..."
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"Y-You... varmint..."
NOTE! Try to keep the death animation in mind.
killed by 
-gasp- such language!
Hey, Draven. Mom said you were adopted!
Killed by 
killed by
: "Hold my hand once more brother..."
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"Better to keep your reputation as a hero than to befriend a filthy rat like me"
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"You think killing me will save your wife from eternal damnation?...ha...ha..."
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"Mundo only wanted to ask you out..."
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"she's a killer....queen..."
killed by
/
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"I always knew you would suck me dry, but not in....this...manner..."
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killed by
"But....i'm the cutest"
Killed by 
Killed by 
Killed by anyone

killed by
: No... how...
"Warwick... why are you doing this?"
Alternatively
"STUPID DOG"
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"You...were always...Father's favorite."
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killed by
"Finally a worthy death for a warrior."
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killed by
"I liked you better when you stank!"
Killed By
killed by
"I CANT BELIEVE I WAS BEATEN BY A NEEEEEEEEEE.......RDDD" Splat
killed by [ANY ELECTRICAL CHAMPION]
"ERROR 404!" "BLITZCRANK 98 HAS CRASHED!"
"You..creeep..."
Hic Hic Hehhh.... hic
killed by 