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The soulshorn stood at the edge of the enclosure. Enclosure was being generous, it was merely a ring of unevenly spaced columns jutting from the rock below. That the stabbing fingers of stone encircled the gyre lent the whole of them the ability to be called an enclosure. Within this space was a cleared circle laid in with bronze and gold and another within that laid in silver. The circles were inscribed with sigils and runes with connotations on the mystic and the profane.
With a gesture the soulshorn levitated a book, itself thickly inscribed, to float before it. The soulshorn, very likely once a quephilim though that was nigh impossible to discern, raised its malformed and mutated hands to the night sky and began to chant. The creature's voice was low and guttural, the language archaic and laden with power. Slowly, individually the chanting awoke power in the sigils below, causing the graven forms to burst alight with eldritch energy.
"We should attack now, stop it from whatever it's doing," whispered K'tal to his companions.
"That is soul energy in those runes. we should watch and wait, understand what that seal is," replied Mellak. Mellak was a soul sorcerer himself and he was likely interested in the end results as much as he was in defeating this soulshorn abomination. Possibly moreso.
"We attack now," Juub'al growled, the short hair on his body raised and his pointed ears canted forward. "It is soulshorn, nothing good can come from this evil. We have an opportunity here and we shall take it." Juub'al's mythlight was starting to flare, a red aura of War. He commanded his companions to flank the creature and the hefted his massive double hand talwar, The others acquiesced, knowing that their leader would not sway his opinion, not now, and began to spread out to flank the heretical soulless.
Moments passed and with a bellow of the power of the Aspect of War Juub'al and his companions attacked. They were met with force. As shades of the dead extruded from the lit sigils and took solid form. Ghastly undead creatures attacked, shielding the soulshorn as it continued its chanting. More sigils lit, the energy of the ritual creeping inexorably toward the center of the great seal.
Summary - A group of adventurer's follow a soulshorn to an ancient mystic seal and attempt to stop the creature from opening it.