Orlash

Orlash is a Rift Guardian, a greatly empowered Terror Demon. He can only be encountered as a random boss in a Nephalem Rift.

In combat, he gains increased damage, as well as the following abilities:
 * Curse of Terror (removed): on each successful hit, reduces healing received by 25% for 10 seconds, the effect does not stack. Identical to that of other Terror Demons.
 * Fast affix and triple attack speed.
 * Teleport affix (animated like usual vanishing, only used to get to close combat with the target)
 * Void Storm (removed): after losing 15% Life and every 40 seconds, Orlash would vanish for 10 seconds. For every second of his absence, at a random point within 60 yards, a 10-yard radius n Arcane blast would be created, spawning 6 Shadow Vermin or two Orcrums (lesser Terror Demons) and dealing damage to enemies within that range. With each vanishing, Orlash changed the type of minions to summon.

As of patch 2.2.0, Orlash lost his Void Storm and Curse of Terror abilities, and instead gained three more:
 * Lightning Breath: identical to Diablo's breath attack, except for its shorter range, instant preparation charge and different color. Can be used roughly every 15-20 seconds.
 * Waller affix with reduced cooldown.
 * Shadow Clones: unlike Diablo's ability of the same name, it summons 3 Illusionist-like copies of Orlash himself when at 50% Life or lower. Illusions are invulnerable, and can also use Lightning Breath, though they cannot change its direction. Normally they cast Breath immediately after summoning, but despawn in few seconds.

Upon death, he has a chance to drop Star Helm.