I am reliably informed that the TV John Constantine appears in an Arrow episode. Appropriately, the comics John Constantine appears in GreenArrow 25. See image. Although JC warns GA that he could be walking straight into Hell, GA meets only the harmless Hern the Hunter who tells him that the forest remembers Robin Hood and will remember Oliver Queen.
This story has:
an evocative autumnal page set in Seattle;
Nottingham (my parents lived there later);
lush green artwork;
ambiguity - Ollie sees Hern on an LSD trip but Hern seems real later.
Ollie must have taken some side roads because he has to ask directions to Nottingham.