I have a few points left over and I'm giving myself two options. The things in the army that the two things will affect are my two hive tyrants (one winged, one not) and my carnifex.
Currently, my Winged Tyrant and the Carnifex have Toxic Miasma... both CC creatures, figured it would help out. But I'm quickly being seduced by the Catalyst and giving it to both of my Tyrants. The two tyrants should be able to cover most of the battlefield with it, and playing against Grey Knights or Eldar, or some other high Initiative based army, it should help quite a bit I would think. Anyway, with the points left, I can do one or the other... any suggestions?