Minion Sentinels are usually found in bunches of 2 to 4, although occasionally they are split by an obstacle (i.e. One in the hallway, two around the corner).
While fairly slow moving, the rockets are able to deal a large amount of Area damage in a short time. It is recommended to clear them carefully from behind a Robotic's Force Field, or use indirect-fire weaponry to kill them around corners. After firing their full rocket pack, they are vulnerable for a short time while they reload.