Perendi

Perendi is a Rift Guardian, a greatly empowered Mallet Lord. He can only be encountered as a random boss in a Nephalem Rift.

In combat, he gains increased damage, as well as following abilities: He is extremely dangerous to melee characters due to his heavy blows but his Cave-In could also be deadly to the ranged ones.
 * Fast and double attack speed.
 * Vortex affix (deals more damage).
 * Teleporter affix (typically teleports to a random player, even if already in melee range with another).
 * Cave-In: summons a rain of rocks across the targeted area (aims at random player), used every 10 seconds. After 1.5 seconds, rocks deal heavy Physical damage to any enemy in 15 yards radius.
 * Minions: every 20 seconds, summons Armored Destroyers with increased life and damage. Initially summons only one per cast, but the amount increases the more life Perendi loses (up to five per cast when he is near death). They actually Deep Strike on the battlefield, being able to do damage and knockback when landing.