i was in the same situation i solved this by using dark charge and guarding talos. on the final wave use your stun the 20min cd and stun again also remember you can use low slash if you want a 4sec break this will also let you get some health back from the 20min CD

i think the assassin are fine check out this vid of some pvp http://www.youtube.com/watch?v=NV4iMa5uP7s&context=C399c65aADOEgsToPDskKVnkI3xAa7i6zSEkn5fueC