"Charge!" The soldiers closest to the woods all charge toward the forest to greet their attackers. Blood sprays into the air as the sharp edges of compressed air cut into the soldiers.
"Ember!" The ground burns below their feet.
"Poison mist!" The air eats away at the lining of their lungs.
"Voltaic sheet!" The sky reaches down to shock their flesh. Like wild animals fit to charge, the humans drive out in all directions to confront the offending fairies. But their focus on the new arrivals has given Foof an opportunity to collect himself.
The lava fairy takes a moment to view the chaos unfolding in front of him before making a move. The Duke is preoccupied with leaving the island surrounded by lava, and the teleporting knight is spread across the ground after being bisected several times. Blood drips out of Foof's ears as he struggles to maintain control of the swirling mass of mana running through him. Despite centuries of hard work and climactic battles, the Mana Vortex technique is still difficult for him to use. While he may be able to control the mana better than Inari, he doesn't have the same capacity as her.
Mana has a natural tendency to explode when compressed. Like diesel fuel, this can be used to cause explosions to preformed work but is deadly when it happens inside a living creature. The density of the mana can be reduced by keeping it moving; the faster it moves, the lower the pressure. By swirling around the mana held inside of one's mana core, monsters and fairies can drastically increase their mana capacity and mana bandwidth; they can use more powerful spells faster and more often than they could otherwise.
But power comes at a price. The internal organs are battered by the violent waves of mana, and blood vessels burst against the pressure. While Foof can maintain the Mana Vortex for longer than anyone else, he's still on a timer. The Lava Fairy raises both hands in front of himself and begins forming a massive magic circle.
"Stop him!" Duke Avaritan notices the crisis just in time and jumps across the lava moat to confront Foof. He flies through the air but falls just short, and one of his legs sinks into the emulsion. "GAAH!"
The Duke quickly pulls his charred leg out of the moat and runs at the fairy.
"Die!" He swings a sword with his remaining arm, but Foof doesn't even try to avoid it. Still focused on constructing the magic circle, the sword slices off his right arm; still, Foof doesn't even flinch.
The blue magic circle activates, and the Concussive pile moving at a snail's pace suddenly kicks into overdrive!
"Get off the island!" Avaritan shouts, but it's too late. The meteoric spell activates and drives into the ground at the center of the island.
'BABOOOOM!'
Most of the troops manage to get away in time, but forty or fifty men are vaporized by the force of the explosion.
"You bastard!" Duke Avaritan swings back around to face Foof, using a small fire in his remaining hand to burn the stump closed on his other side. The Lava Fairy quickly flies backward to avoid the mad slashes of the noble. "I'll cut you into pieces when I get my hands on you!"
With a smooth wave of the arm, Foof liquefies the ground at the Duke's feet. The Noble stumbles forward as he tries to regain his footing. Using that brief moment of occupation, Foof manipulates the lava to flow out of the moat and attack the troops. The snake-like molten tendrils reach out and grab one man after another. Screams erupt from the crowd as the recently escaped men turn to see their prison chasing after them.
"Endothermic Pile!"
"Accelerate!"
"Electrostatic Binding!"
The Duke's forces throw out one spell after another to impede the progress of the gluttonous snakes, and some even resort to holding the beasts in place with static electricity. Unfortunately, the snakes neatly pull up the soil, binding them and using it to increase their mass.
"Displace Soil!"
"Liquefy! Bind!"
Several other mages have similar ideas and try to create an earthen wall or bury the lava snakes, but it only makes the glowing beasts larger.
"AAHHHHH!" A blood-curdling cry is released as the first person is devoured by a lava snake. Nearby soldiers can only wince at the grotesque sight.
"First Gate: Open!" A samurai falls from the sky with a flash of steel,, and the lava snake is rent in two. Baron Kobayashi stands before the troops with his noble figure. "We just need to hold off the lava beasts while the Duke finishes off the fairy controlling them! The rest of you spread out and attack the small squads of fairies harassing us!"
Those words alone are enough to turn the battle around. Several people near the Baron join him in fending off the lava snakes while the remaining mass of humanity spreads out into the forest like a flood.
"Flar-AAHHH!" A young fairy is bisected before she can finish casting her spell.
"Leave the black mana stone for now. We can always come back and divvy up the spoils later!" A captain shouts to keep his subordinates focused. Each mana stone is worth enough to serve as a retirement plan if one were to sell it, but that only matters if they manage to survive. Dead men can't use credit. "Keep moving!"
"Fiva!" Another fairy reaches out to his dead companion but is quickly restrained.
"Leave her! We need to pull back!" Hai shouts at him to grab his attention.
"…"
The young fairy doesn't respond but obediently flies back into the woods.