Omni The Magnificence

Omni, is secretly the power behind the throne and de facto leader of the Troobian Empire.

Appearance and Powers
It was originally a giant brain housed in a tank in a room on Gruumm's spacecraft. It has a single eye on a tentacle-like appendage. After collecting resources from several planets, it's servant, Emperor Gruumm completed Omni's Magnificence, a colossal biomechanical body for himself that Gruumm created with the stolen resources.

Omni possesses psychic powers and is able to both talk to and harm Gruumm from a distance, as well as brainwash people into serving him, such as Mora. It seems that he can only brainwash more weak-minded people, Gruumm didn't appear to be brainwashed as he tried to argue with Omni's orders, albeit futilely, Omni had to manipulate Gruumm to do his bidding. In his Magnificence, he is large enough to hold a Megazord in his hand and wields incredible destructive power.

In his original form, Omni has a rather normal voice. But as the Magnificence, Omni has a more booming godlike voice.

Bio
It was mentioned on a few occasions throughout in the season, but was finally revealed at the end of the episode Insomnia, making Mora pledge her allegiance to it. In Endings, Part 1, it not only "spoke" for the first time (yelling at Gruumm over his petty feud with Cruger), but its name was revealed. Omni's reason for attacking Earth was to drain its resources for a weapon in development that it refers to as The Magnificence, a colossal biomechanical body for himself that Gruumm created with the stolen resources. Once the Terror Spacecraft locked in, Omni was connected to his body and used it to fight the S.W.A.T. Megazord, having the upper hand until Doggie Cruger opened an access panel from the inside, allowing the Megazord to deliver a maxed-out laser blast, causing the Magnificence to implode and taking Omni with it.

In an interview (9:26 in), Greg Aronowitz stated that "Gruumm has always been Omni's puppet... [Gruumm] has power, but he has issues and he has weakness, and Omni has taken advantage of that for as long as time can remember." 

Omni or The Magnificence?
The creature has been inconsistently named throughout the series. Early on, the name "The Magnificence" was used for the creature, but around the time of its actual arrival on Gruumm's spacecraft, the name "Omni" came into use, with no explanation, and was treated as if it had been the creature's name all along. Eventually, Gruumm's long-term plan proved to be the creation of Omni's body, which was called The Magnificence for the rest of the series.