It's a little bit difficult to translate "って" into English. Your example means "What kind of monster is AKANAME? ",right? In this sentence, "is" is same as "って". If you want to use another words, you can say "〜というの(ものorひと)は". It means that "垢舐め「って」どういう化け物?" ="垢舐め「というのは」どういう化け物？". Does this make sense?