Wraith tribal might be a fun direction to push the deck, but not including cards from outside the set might make it a bit harder to be consistent. That said there is not much support for the tribe specifically outside this set.
Since the deck comes with [[Living Death]] if you could get all nine [[Nazgûl]] into your grave yard you would be looking at 9 instances of the ring tempting you and 81 triggers to put a +1/+1 counter on each wraith you control.