User blog comment:Grymstorm/Pentakill, Looking for Fifth?/@comment-1990160-20110830174029

Presuming that Sona is going support and not AD Sona, it'd have to be an AD carry. As is, they have:
 * Mordekaiser (AP offtank)
 * Sona (support)
 * Yorick (AD offtank)
 * Karthus (AP carry)
 * ??? (AD carry)