To detect that you are in your multiline section you can use the range operator (meaning "from..to") and regular expressions.

/^war.*[{]/ means a line starting (the ^ means start) by war, followed by any character (the .) many times (the *) and a { ([] contains a list of allowed characters).
/[}]/ is a string containing }.
/^war.*[{]/../^war.*[{]/ checks $_ and is true between war.*{ and }. You can try this:

while (<DATA>)
{
  if (/^war.*[{]/../[}]/)
  {
    $_ = "==> $_"; # Show the matching lines
  }
  print;
}

__DATA__
bla
bla
war eligible, init =0*DEC0, ev (VARIABLE){1*BIN0,2*DEC3,6*BIN4,
& 5*BIN43,6*DEC32, 
& 5*BIN43,7*DEC32}
bla
bla
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Now the tools you may need to complete the work can be: chomp to remove the newline, and tr to remove a character (or maybe s for a more complex modification)