Shadow of evil, could they be referring to the Shredder? Is that the season one final by chance?
Don't know about that Raph episode, when Leo suspects things about people it normally turns out to be the bad guy. So, it's either the introduction of Casey or an unknown dark shadowy figure.
I'm itching for that portal episode, wish we got a preview for it like the last batch but than guess it would spoil things. I'll be back to give my feedback of the latest episode tommarow