You summon your demon.
A vertical beam of burning bright light illuminates the cave accompanied by cacophony of screams of pain, screams of sadistic pleasure and insane laughing. Once your eyes stop watering you can see large creature dragging and slithering through the gates of hell.
Now lets describe this thing. Its back end is similar to eel, but bright blue and yellow in color. Long and slimy. Its "tail" ends with a head of snake. Its upperbody, or front, is seemingly like horse's, but its shoulders stick out of the body a good bit before becoming normal equestrian legs after exposed ball joint. Instead of hooves it has long webbed claws wielding seemingly normal halberd. Its neck is strong and very horselike, but head is that of flattened insect featuring three long horns pointing backwards. On its back it has large pair of dragonfly wings. And over all that it is wearing a black and silver leather cuirass.
As soon as the demon is fully on this side the gates slam shut and disappears along with light. A moment later air around demon starts glowing with pink light letting you see around.
The demon looks around looking for its summoner. Failing to find anything large it finally sets its compound eyes on you.
"Tsk. Such weakling summoned me? How dissappointing. Let me guess, you need me to kill your opponent, yes? Let me warn you; if it isn't worth of my time I will turn you into my puppet and you will suffer."The demon slaps a wall with its tail and gates of hell reappear instantaneously and slam open with great force.
"TRASH! Time to hunt! Save strong ones for me if you find any!" it yells at the gate. Wailing and screaming intensify and a few seconds later a horde of lesser demons pour forth. They look like odd mix off lion and great wolf, and bring along horrible stench of rotting meat, burnt paper and hot metal. Even fires of the hell and pink aura generated by this god damn chaos lord of yours is darkened by their presense. You can't tell how many came through before they disperse into dark tunnel ahead, but too many anyways.
You are lucky man. Or not, depending of strength of your opponent. You better pray he's powerful enough or you'll be in world of pain.
You didn't notice this before, but is rather foggy here.