I stealthily creep into her room, wand at the ready (Ebony 14 1/2 inches unicorn hair core, reasonably supple) My owl flies in, her dark feathers blending in perfectly.
I creep up to her bed and whisper
Avada Kedavra!
Perfect
She's gone!
Serena lies dead on the bed
Her last remark on her tongue never to be spoken
Everyone welcomes me as a hero
"YOU KILLED HER YESSSSS"
"SHES FINALLY GONE"
"BAM"
It's the most beautiful thing ever

(A/N I will be taking requests from here on out, what do you want to happen to this evil girl?)