I like using Nightmare with Vortex. You can get a decent Nightmare half deck fairly cheap. The Vortex half depends on what your budget is, though. Cards like Dagg, X-ODUS, and Dregn are pretty expensive, but they are very useful.
Oflgn or C Beast can be used instead of Dregn. You may use Lehrg or Lovhak instead of X-ODUS or Dagg, if you cannot afford them.
C Wing, Cyb Lhia, and Neloe are some good 2 stars. Deea, Sunder, and Qorah are good 3 stars.