I'm not sure what the result you want is. The following works for me:

Q:\>perl -we "$s='corion'; for (1..1000) {$s++}; print $s"
corkaz
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Maybe you need to increment by more than just 10, or maybe you want to clarify what you want to do. A different solution might be the following, which rotates all characters by one:

Q:\>perl -we "$s='corion'; $s =~ tr[a-z][b-za]; print $s"
dpsjpo
[download]

Maybe give us the expected output, the output you get and the code you tried.