A small, invisible flying mercenary that provides vision and can see invisible units.
Sentinels are discrete scout drones created by the Gearmaster, leader of the Mercenaries' Engineers. Able to see far, their sight comes at the cost of easily being shot out of the air. Hamaliel obtained favor with the Mercenaries by helping the Engineers design the Sentinels with cloaking fields. But for everything the Sentinel helps Arctora's armies see, the Gearmaster of the Mercenaries can also see.