True, after all a living organism couldn't have endless energy. My guys sure as hell don't and regularly use tech to keep powered up when possible. And not to mention when a sentient uses magical field I don't think they'd be able to move or go on the offensive [my guys certainly don't] so it's fair enough; I just dunno about spamming them like that. 

However I don't see why a shield couldn't be overloaded by spamming projectiles at it in quick succession to overwhelm the whole matrix of how much energy is fed into it. 

Planetary energy shields probably would only exist on certain worlds worth setting up all the infrastructure required for that on; I can't see a developing colony having one.

However, concerning the Le'r all I can ask is:
Worms that eat through titanium that you can send in the swarm?

And I thought sentient hyper-telekinetic spheres of flesh would be pushing it which is why I gave them logistical limits.