Set of expressions? Bah! Why not just use a single one? ;)

use re 'eval';

my $username = "jryan";
my $password = "perl6rules";

print $password =~ /
    (?=  [^\d]*\d )
    (?=  [^a-z]*[a-z] )
    (?=^ (?: (?!(.)\1\1) . )+ $)
    (?!^ \Q$username\E $)
    (?!^ (??{quotemeta reverse $username}) $)
    ^\w{8,12}$
/ix ? "(-:" : ")-:";
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Note: I also assumed you meant "cannot" for rule 5.