Prologue:

There are some events in time which are fixed. They must always take place; They cannot be changed or prevented, only delayed. One such event was the sealing of the Mystix.
No-one knows the exact age of the Mystix, except perhaps the Great Beings and Ignotus himself; It has been said by some that they are as old as the stars themselves, if not older. They were humanoid, almost like bats, with metallic armour, webbed feet and heads similar to those of the Vahki. They were the Great Beings' first attempt at intelligent life, and Ignotus was the first among them. He did well when tested, and the Great Beings created hundreds upon hundreds of creatures like him. Soon, when they thought the Mystix were ready, they set them free to walk among the Agori and Glatorian. That's when the trouble began...
The Mystix believed themselves to be infinitely superior to all the other beings who walked the surface of Spherus Magna; They killed them, they enslaved them, it seemed that there was nothing that could stop them. Eventually, the Great Beings themselves had to intervene, and banish Ignotus.
Ignotus took the other Mystix with him, creating an island in the middle of the Endless Ocean. However, when the Shattering came, this island was separated from Spherus Magna. There was panic for a time, but eventually they learned to live peacefully.
But when Mata-Nui came crashing down, a great wave drowned their island; Few Mystix survived, but most of those that did followed Ignotus to a new island, where they lived in a large cavern that would one day be called 'Onu-Koro'. But it would not be long before Ignotus found yet another new species to fight against...

Aru thought over these things as she walked down the tunnels. She wondered where everything had gone wrong, and how. Here webbed feet made no sound as they touched the dust. She was of average height for a Mystix, mainly blue, with silver armour and some lime-green on her limbs. Eventually, she believed she had reached a point at which it was dark enough for what she had planned.
"Makuta!" She called out, expecting that she would be heard, for it was said that Makuta not only lived in the shadows, but was, in fact, the shadows themselves.
Suddenly, the darkness almost seemed to grow darker, and a chill wind blew, despite having no place from which to originate. Then, two red eyes materialised in front of the Mystix.
"Speak." The Master of Shadows commanded.
"I require... your assistance." Aru replied.
"Assistance?" The Makuta asked, intrigued. "I have promised a year of peace; If this 'assistance' requires an attack against the Matoran, I cannot help you."
"No, it does not. In fact, in a way I am helping them." She said. "I want you to help me remove Ignotus."
The Makuta had heard of Ignotus' attempts at conquest; He had planned to destroy him at his leisure, but decided that it would be best to remove him now, while the Mystix was offering.
"In the cavern your species called home, there is a cave to the side. You must bring Ignotus and the others there. Then, I will seal him and the rest of your species within."
"Then it is agreed." Aru stepped back, returning into the shadows.

Ignotus stood in front of his army. He was completely black, except for some silver armour on the upper parts of his arms and on his front and back. He had spiked black armour on his legs.
"Tonight, we shall battle! Tonight, we shall take back that which is rightfully ours! Tonight, we shall FLY!"
The gathered Mystix erupted into applause. They were inside the cavern that the Makuta had suggested to Aru, and that Aru, in turn, had suggested to Ignotus. She slipped away, silently, unnoticed. Or so she thought...
Kraal was one of the Mystix trusted most by Ignotus. He was completely grey – even his armour was a metallic grey – and had cold, blue eyes. He noticed Aru slipping away, and followed her.
When Aru exited the cave, she looked behind her. A wooden door appeared to grow out of the rock itself, plank by plank, nail by nail.
"They can never escape." The voice that had said this belonged to the Makuta, and he was right. The door could only be opened from the outside, as it was only a door on the outside; On the inside, it was simply a wall. The Mystix were frozen in time, never stirring, never aging...
Always waiting.