Sentinels are a type of Purifier. Karax added them to the Daelaam's army after retrieving data on the Purifiers from Glacius. Unlike the traditional zealots, sentinels are fully robotic, making them more expendable. They are outfitted with a basic AI instead of a personality construct, and on-board systems to rapidly repair them to combat-ready status should the sentinel be destroyed.
Sentinels were also found with the bulk of the Purifiers on Cybros. After Artanis recruited the Purifiers, the Purifiers would make use of sentinel zealots throughout the rest of their campaign.
The sentinel is one of three melee warrior variants that the player can choose from in Legacy of the Void, along with the Aiur zealot and the Nerazim centurion. The sentinel has a reconstruction ability that revives it shortly upon its initial destruction, at which time it is restored to full health and shields. This gives the sentinel greatly increased longevity, in exchange for lacking the damage output of the Aiur zealot or the support capabilities of the centurion. Reconstruction has a long cooldown, and if a sentinel is destroyed while the cooldown is active, they will be lost. Thus, sentinels should be allowed to pause between engagements so the cooldown can wear off and they will avoid unnecessary losses.
Another critical difference between the sentinel and the other zealot variants is that sentinels are mechanical units, not biological. In addition to enemy damage bonuses affecting them differently for this, this means the sentinel can be healed by the Spear of Adun's reconstruction beam ability or a carrier's repair drones, which further increases their durability in battle.
The zealot charges towards a target enemy unit or structure, boosting its speed to 8.47 for the duration. The zealot must have clear ground pathing to their target to reach it. Also increases the zealot's normal movement speed to 3.85.
In Legacy of the Void, Charge deals 8 damage on impact.