Graham,
I already proposed these in the dev feed chat, but just to make sure:
"Control Disruptor Grenade" - Servos and drones caught in the blast will become (temporarily) uncontrollable and start attacking random targets (including the owning players buildings, drones, servos).
"Power leech" - Like a tazer (kind of wire connection), drains health from targeted servo/drone and gives health to user; Connection breaks when distance exceed a certain limit. When used on ally, pumps health to your ally.
And two new ones:
"Last resort" - A self destruct (for your servo) that destroys your servo but does damage to the area proportional to the health of your servo.
"These are not the drones you are looking for..." - Creeps do not attack the servo or the drones within the servos sphere of influence.