Battle of Three Worlds

when they emerged on the other side of the doorway,

they were standing above a battlefield in the sky with the doorway behind them radiating light

a black swarm with large black mountains behind them covered in nasty black-winged spider bugs with human-looking heads and torsos

but they had nasty pincers for arms and bug eyes and giant spider legs and all armed with spines and huge claws under their belly for grabbing things from above 

and their bodies were black and armored and tough and glowing energy spilled out of their mouths like putrid vomit that made the ground beneath them blacken and corrode like some kind of acid

and the other side on this battlefield was filled with an army modern radical vehicles armed with guns and the ability to drive fast across the terrain

flying robots with rockets in their boots customized from vehicles similar to Magnetic world that were armed with large guns and swords to fight the flyers in the skies