You can use the $str identifier and /tokenize to perfect your script, along with the use of $r or $rand to randomize the text color from 4 through 13:

Scream {
  var %x = $str($+($chr(22),Scream:,$chr(32),$+($chr(3),$r(04,13),$1-),|),5)
  tokenize 124 %x | msg # $*
}