Agni awoke very angry and was not surprised to find himself in another cage. He saw that it was wooded, great, he could escape. But he looked around and saw bookshelves and desks with paper. He saw a loft with a bed too, what a strange prison. The rest of the structure was wooden, and he had to restrain himself to just enough to smash the cage with his bare hands and force his way out.
He looked out a window to see a rural town location populated by the ponies that had managed to capture him. He still had no explanation on how a god could be subdued by a mere mortal, or how he got here, but he had to get out. He felt that the ponies only captured him because they feared for themselves but that wasn't going to be enough to subdue Agni's rage. He simply broke a small window and after a few minuets of burning he was able to get out of the... tree building facing towards fields and a large forest. Perfect for him to burn.
He thought about using his fire to speed up his travel, but it would leave a very noticeable trail, but that's fine because he never retreats. After some effort he was able to get past the field with a flaming speed, but he simply didn't have enough to get all the way. He walked until he reached more fields of more orderly trees and a farm house.
He figured that this was a source of agricultural supply to the town, and they could do without some apples for a while. He was a god after all, they might be able to hurt them but they couldn't kill him. He lit flaming balls of fire and he lobbed them at the trees, reveling in how they caught fire like dry brush, and he felt his power grow as the blaze raged around him. Now he could see figures coming out of the farmhouse to stop the fire, and he quickly sprinted away, laughing.
Twilight had no idea how it happened. One day after the princess sent her a letter about another being like Ah Puch & Bakasura being found, and Applejack's farm spontaneously catching on fire. Applebloom, Big Mac, and Applejack ran around, trying to stop the fire with buckets of water, and Twilight and Rarity shot water at the flames with their horns while Fluttershy and Rainbow flew back to Ponyville for help.
The blaze was too large, and in no time at all, a large portion of Sweet Apple Acres was a charred wasteland or still had cinders burning it. Applejack didn't say anything. Applebloom began to cry, but before she could Big Mac broke out in hysterical sobs and her and Granny Smith comforted him. Twilight could barely comprehend how this could happen, how it just magically caught fire. If Ah Puch was with them he might have been able to help, but he was in the Everfree talking to Zecora, who he had an interest in.
"A-Applejack... L-lets go back to the library," Twilight said to her. Applejack responded with a dead gaze and they walked back to Ponyville. Ponies were still rushing to the farm when they arrived, and many offered Applejack her condolences but she ignored them. When they got back to the library, Twilight was shocked to see the wooden cage Celestia had shipped to her overnight was charred and broken. And a fiery path led from a broken window.
Straight to Sweet Apple Acres.
Applejack wasted no time in running back to the farm, this time her face bright with anger. She returned in no time flat and surveyed the path, dismissing the burned trees, she saw it led into the Everfree forest, and before Twilight could even catch up, she sprinted in. Forgeting her fear of the forest and whatever burned her farm, it would pay for what it did.
Agni wandered through the forest in boredom, he figured he'd take a break from burning things and explore part of this world. He just kept walking though the overgrown trees and brush when suddenly, a strange figure leapt out in front of him. It looked like a wolf, but it's body was completely made of wood, with glowing green eyes and sharpened twig teeth. Agni snapped his fingers and the wolf went up in flames, yelping before its body turned into ash, Agni kept walking. He soon became bored, and started thinking again about igniting this forest, but he decided against it. Some things must be spared the fire's wrath for the good of all.
He eventually got to a part of the forest where the trees blocked out most of the sun, and was surprised to find a small wooden shack with green smoke wafting out of a window. His interest piqued, he tried to inch forward, but before he could get to the window the door flew open and a gaunt figure exited. He was a skeletal humanoid with black skin and a threatening mask with glowing eyes. It grumbled to itself before walking along a dirt path back the way Agni came. He had never seen this individual, but it was the closest he had seen to a human in this place, and the aura of power that he gave off was extremely strong, much like a god.
He instead followed the god back to the village, he decided that a few more bonks on the head if he got caught was worth learning more about this thing.
Anyways, he was already going to repay the ponies for their folly the first time.
Applejack bounded over broken logs and overgrown brush following charred footsteps that led deep into the forest. Fear and exaustion tried and failed to bring her down as she searched for the evil creature that had burned down her farm. The farm was her life, the one thing that she had to hold on to was now gone, burned by some uncaring devil. They had never expected anything of this severity when Celestia sent Twilight that letter, but apparently Celestia hadn't seen the worst of the creature, and Applejack vowed to stop it.
She finally reached Zecora's hut, and she saw that the steps led back down the path they take to get there, and wasted no time following them back. She doubled her speed, obviously the creature thought it hadn't finished them off and went back to complete the job. She had to try to reach Ponyville before it and warn Twilight or catch it on the way.
Whichever came first.
Agni had been stealthily sleuthing his way to the tree-house, and it was working fine until someone screamed. He was halfway from where he started and the tree until some pastel horse-creature spotted him and let out an ear-piercing scream. Agni flinched and his body engulfed itself in flames in his anger. Fortunately, the screaming pony was also the smart pony, as she ran as soon as Agni turned his burning gaze (literally) toward her. Agni calmed down, but it was too late. The entire town had heard him and seen the smoke, now horse-creatures were screaming and running around in a panic. The door of the tree-house flew open and out sprung a purple horse and the thing he was following earlier.
Agni was flipping through his options now. He didn't want to burn innocents any more, and at this point, flight was the only other choice. He tried making a run for it behind some small colorful buildings. He was blasted off of his feet, and landed into a smoldering pile of rage. The purple horse had hit him with a beam from its horn, and he prepared to set the thing on fire. But the other being had other ideas. From his staff, a small, smokey form emerged from it. Agni tried to follow it as it flew towards him and started to take the form of some sort of bird. Too late did Agni realize the distraction, he looked down at his feet where a green circle glowed below him. Suddenly a amalgamation of bones sprung up from the ground, encircling Agni in a cocoon of rib-bones and femurs that he couldn't escape.