This build requires your pet to have Synth Fiber equipped, because that makes the Dispensary's health orbs give you 110 energy due to Equilibrium.
To kill higher-level stuff, recast Sonar a few times to get those sweet, sweet overlapping weak spots.
I have 160 range because it seems like that makes it hit enemies before they get close enough to start shooting.
Ferrox, KBramma, KNukor, and an energy-regain Zaw are good choices, either for cleanup or if you mess up and let your energy get too low.
Note that this build can definitely be optimized, I just haven't because I haven't gotten around to building [Banshee Prime].