a simple edit for this,
why set many vars to this? by the way, where is the var for %bot-fun?
and when the var %bf is called on script?

on *:text:!kill *:#:{
  var %kill $rand(1,4), %y msg $chan
  if ( %kill isnum 1-2 ) {
    %y $$2 died from the wounds you have inflicted. He's swimming with the fishes now.
    %y $replace(%kill, 1, tried to strike back but failed completely, 2, couldn't contain $$2 backfire. 7 $nick died from the wounds he inflicted)
  }
  if ( %kill isnum 3-4 ) {
    %y $$2 Suffered but is still alive.
    %y $nick $replace(%kill, 3, couldn't contain 7 $$2's backfire. 7 $nick died from the wounds he inflicted., 4, tried to strike back but failed completely.)
  }
}

for those genious that will say something, i will not do it using regex
and i didnt forget about a ''flood protection''

by the way, as i said, simple edit based on his code