Doppleganger

Doppelganger is a boss modifier in Diablo III. The function of the modifier allows the boss monster to create a clone of itself. The spawned enemy will be clearly labeled in its nameplate as being a "Clone of X", "x" being the monster it was spawned from.

Doppelganger is one of the boss modifiers that isn't reliant upon an elemental theme, and is utilitarian in purpose. The clones produced have the same health points as the original, so it is in the best interest of the player to focus on the boss itself before it can spawn more clones. The clones also retain the attributes and modifiers of the original, making this a potentially lethal modifier when combined with another mod such as electrified or nightmarish. It is currently unknown if bosses with both linked and doppelganger mods can spawn, and if so, how that combination would operate.