sort and How do I sort an array by (anything)?

Here's one way to do it with fairly complex sort criteria and a Schwartzian transform (assuming I've understood the requirements correctly):

#!/usr/bin/env perl
use warnings;
use strict;

use List::Util 'shuffle';
use Test::More tests=>1;

my @expect = qw/
    frooc froof froz
    ebaz eyun ebxu
    quz qun que /;

my @input = shuffle @expect;

sub special {  # sort routine used below
    $$a[1] <=> $$b[1]  # first sort by categories
    or  # then sort by the desired condition per category
    $$a[1]==1 ? $$a[0] cmp $$b[0]      # category 1 (/r/)
    : ( $$a[1]==2 ? $$a[2] cmp $$b[2]  # category 2 (/^e/)
      : $$b[3] cmp $$a[3] )            # category 3 (rest)
}
my @output = # sort with Schwartzian transform
    # Step 3: get back the orig_str out of the array
    map { $$_[0] }
    # Step 2: sort with the "special" function defined above
    sort special
    # Step 1: each item -> [orig_str, category, third_chr, last_chr]
    # where category is: /r/ => 1, /^e/ => 2, rest => 3
    map { [$_, /r/?1:(/^e/?2:3), substr($_,2,1), substr($_,-1,1)] }
      @input;

is_deeply \@output, \@expect
    or diag explain \@output;
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