The skyshield is useful with shield up for static units to provide long range firepower. DE don't really have any of that unless you want to unload your trueborn on it. The other alternative is to make sure your deep striking units don't scatter. IIRC though fortifications have to be placed in your own deployment zone, so unless you're banking on your enemy getting into your deployment area before scourges/hellions etc arrive to my mind you're just as well off deploying them from your own table edge.
Didn't stop me buying a skyshield though to either use as an objective or for my marines/tau etc.
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