Drunk Rhino

I'm not sure what category you've built this deck for but Pristine Talisman might be worth having a look at.

Hypnotic Specter is a cheaper card (mana wise) than Abyssal Specter and appears to do almost the same job.
Also a couple of cards similar to Duress are Inquisition of Kozilek or Despise, but that depends on what you're trying to do with it.