I love a good tactic, thanks. The engineering wars continue....Some of the (higher end) NPCs runn SCBs (Shield Cell Boosters) - you can see them recharging the shields with a nice pulsating animation of their shield. Several options here - I usually try to hit them hard and fast to bring down the shields (SCBs only work if there's some shield left to recharge), after which they usually take a long time to come up again. Other people like Railguns with the Feedback Cascade effect, which will directly damage the SCBs while they're in operation.