Shattered Mirror Universe

BZPB-174, called the Shattered Mirror Universe by many after its famous device, is a bizarre alternate universe.

Here, Kakamu led the Brotherhood of Makuta, Ynot was the treacherous second-in-command, and Zev Raregroove is an evil genius with a love for tying people to traintracks. In addition, this universe's Klak was killed by Caiaphus (who trained Tahar'ok).

Sick of enduring thousands of years of war, a Great Being named Okk created a device called the Shattered Mirror, which he intended to be used as a vessel to transport people to another reality. It was destroyed following a huge battle shortly after its arrival in BZPB-108, but their leader Trantoshen escaped back through it into the Shattered Mirror Universe. He spent a year building another Shattered Mirror, which he sent into BZPB-108 after completing it. The Invasion through the Shattered Mirror II followed, and ended with the ship being smashed into the ground by Blackout and Weapon X activating on its underside, which decimated the battleground and shorted out the SMII's power systems. As a result, the SMU is now completely cut off from 108, resulting in many of its former inhabitants being trapped in 108.

Trivia

 * The SMU was the first major alternate universe to be introduced in BZPB, which is also why it has spawned the most alternate characters.