LOTR: A Spell of Concealment [https://www.youtube.com/watch?v=gqRPifHxIjg&t]
Eight Years Ago, Earthland Continent
The Balam Alliance looked around at one another. All these mages looked at each other with a deadly look and that brought arrogance
And with arrogance came impatience
Hades: Okay ... which of you decided to call this meeting?
Brain: I felt like it was you or our demonic friend here.
The two human mages looked at the chief of Tartaros.
Mard Geer: I honestly had nothing to do with it.
Azuma: Well, who the hell was it?
???: That would be me.
A dark and monstrous voice, sounding like a thousand demons speaking like one. The Dark Guilds all looked around, to find a mass of darkness that seemed to suck the light out of the room.
Ultear: And what are you supposed to be?
All the mages nodded. Whoever it is, he better have a good reason for that.
???: I? I am something none of you could understand.
Cobra: You calling us stupid or something?
At the words of her master, the great viper hissed furiously at the shade.
???: Oh not at all, merely… unable to grasp the power before you.
Hades: Enough of that! Let's eliminate this intruder so that we can resume our quest to find Zeref
[1:19]
A bestial growl was heard before the Shade's power flared to life, what was merely darkness was now shadow and flame.
???: FOOLS !!! Do not test my patience or my strength!
The dark being threw all these opponents against the walls. Despite being Fiore's most powerful black mages, none of them could compete against this monster.
Mard Geer: H-His power is greater than Lord Zeref !? Impossible!
???: Who do you think who cursed him in the first place ... little Balrog?
The demons were amazed, the being in front of them knew their biggest secrets
Kyôka: C-How do you know this word?
???: I know everything about you. Just as I know of the spawns of the Blue Wizards which inhabit this continent. For I am the Dark Lord Sauron!
And in that moment the Dark Lord's armored form was shown silhouetted in the flames
Sauron: YOU WILL OBEY!
...
Today
And so the Dark Guilds obeyed their new master. They were given just one task and one alone:
To cause Chaos.
The Dark Lord knew that Zeref was still among the living, he was the origin of the Dark Wizard's power after all. He needed the Mages of Earthland to have enough on their hands to where they couldn't look beyond their own continent if he were to achieve his goals. But they also needed to be weakened in order to not be a threat to his future plans.
And it worked perfectly, the most powerful of the guilds, Fairy Tail, had just their lost main people to his personal project: Achnologia.