The key to eldar is to pick something and do it well, trying to do everything is inefficient at best and cataclysmicly disasterous more often than not. A farseer in a transport is not doing his job. Your paying for those powers you need to use them whenever it's advantageous. guide/fortune and doom/mind war are the obvious options, but dont discount eldrich storm for spinning tanks to get at the tasty poorly armored backsides. And remember if you are using 2 powers a turn that runs you higher risks of instant death from a perils of the warp hit