Due to the nature of Precepts, it is best to place Sacrifice in the very upper left slot, so the sentinel will not prioritize using other skills such as Crowd Dispersion or Ghost over reviving the player. For example, if a Shade has been modded to prioritize Ghost first, it cannot use Sacrifice to revive its owner until Ghost ends.
For a short time after Update 10.6 this mod could have been acquired via Transmutation. This was due to a bug where all mods, including unreleased ones such as this one, became obtainable through transmutation. This was quickly fixed, but players who obtained the mod this way were allowed to keep them.