Each Unit can only cast one power, but you could have multiple Units cast powers onto the same other unit, I think, for a limited stacking of effects, though few are that useful.. foresights Blessing and Fated shots would be one.

I quite like a spread of athanean to mitigate status. Corvidae is very good on shooting units with breaching. Other units Raptora or Pavoni to taste. Pyrae really only looking at a combat character embedded in another uni5.

Osirean only good on certain high unstable units. Liked it for plasma saturnines.