Another story from my car campaign:
My little hero encountered three red crystals covered with dark runes. When activated, black ooze would shoot out from the crystal and form a goo-creature around it. The first one turned into a giant spider which he tracked down and defeated and the second turned into a giant caterpillar in his hometown and he had a dramatic fight where he just barely managed to protect his sister from it.
He carried the last crystal around with him for a few sessions before he realised that he should destroy it before it too transformed. He was on the top of an extremely tall peak at the time and wanted to throw it down a crack, but failed the roll to successfully destroy it. Black ooze shot up from the crack and another goo-creature took form. I let him say what it looked like and following the pattern I had already established with spider and caterpillar, he decided that it was a phoenix.
With a hoarse squawk, the huge red-eyed bird crawled out of the hole looking like an oil spill victim. The hero did some quick mind gymnastics and came to the conclusion that the abominations weakness must be fire. He tossed a lit lamp at it and the whole thing caught on fire. It didn’t seem healthy, but that didn’t stop it from scrambling across the ground, charging at the hero while black burning ooze was sprayed in all directions.
The hero pulled out his volatile wind wand as a last ditch effort and with a failure he blew himself and the burning phoenix off the peak. While plummeting through layers of clouds he armed his crossbow and fired at the flapping and squawking creature falling with him. Goo does not make very effective wings.
Another failure was rolled so I asked him: “Do you manage to defeat the bird and continue to fall or do you miss the bird and get caught by it?”
The bolt hit right between the eyes and shattered the crystal inside, sending red shards out the back of the bird’s head. Blobs of goo fell off the shrivelling body and flew upwards until the whole creature dissolved and disappeared above.
He couldn’t see it through the clouds, but he knew the ground was getting closer and closer at a blinding speed.
…and that’s when we reached our destination and ended the session.
“No, please. Not a cliff hanger. Not again. Please…”