Appearance and Behavior EditThe Bone Sentry is basically a stronger version of the Bone Ranger. While he behaves absolutely the same, he wears chest armor, a helmet and holds a huge axe instead of the saber in his right hand.
Basically the same as the Bone Ranger, except that he throws three axes at once with about 30° angles between each of them. They also have about three times more health than their weaker counterparts.
Take them out before the Rangers, since their attacks actually cut off your evasion paths.
Since they have quite some health and don't move while attacking, you could use Area-Damage-over-Time effects (ADoT) to take out whole groups of them without wasting too much mana, especially since they can be trained* (for example with the Poison Amulet or the Fireweaver Bomb).
*See comments for explanation of the train effect.