Helping others kill Sentinels since now.
If there are more than 2 sentinel in an area and they both activate you run at them and keep running forward. If you run back they will incinerate you with their death rays because they are preaimed at you.
The way you escape is how you will also kill. Each sentinel will spawn a few laser bots. In order to remove the shield that the sentinel has, you must kill the laser bots.
How you kill the bots with ease, you run towards them so that they have to redirect their lasers and you immediately, once able, shoot at them quickly.
After that happens the sentinel will try running away leaving a laser carpet, run around it and shoot it. Continue until it dies.
This is easily accomplished with a combo of 3; healer, shielder, and nuker.