Bursting Mana Shard

<The piece of obsidian you hold in your hand is hot to the touch. Light violet strands of energy exude from the cracks where it broke from the creature lying in front of you. This crystal is bursting at the seams with potent arcane power. The endless possibilities of what you could achieve with this item rush through your mind, before a faint whispering voice enters your mind. Unintelligible at first, its volume increases the closer you hold it to your head. Now able to recognize the voice it repeats one word over and over again: Desolace.>

<The book you find on the altar has numerous rituals and incantations. One of them, presumably the spell the cultists were currently practicing, speaks of a summoning - the summoning of a dark entity from beyond the Twisting Nether. What is needed is a conduit of great magical properties, as well as some implements. Your thoughts race back to the mana shard. Perhaps this is its true purpose?>

<You lay everything atop the altar and recite the spell from the grimoire. With each passing word, the air grows heavier and lightning strikes the sky. The mana shard breaks, releasing a strong shockwave. Moments later, a rift opens above it and -? out of its boundaries - a terrifying nether creature emerges!>