Night Templars are simply High Templars for the Dark Templar clan. They have no primary attacks, but acquire special psionic abilities to support the Protoss army. The Night Templars have learned about how topsionically connect to the astral dimension and use it as the supporting ability. Similar to the high Templar, the Night Templar has 2 special abilities including:
Astral Cage Imprisons the targeting unit in a dimensional rift, takes it out of play for 6 seconds. Spirit leak Absorbs 20% of ground units in the area of effect's Life points and converts the life points into energy points for the Night Templar. This ability costs the Night Templar's Life points directly instead of Energy.