The Obsidian Tower

The Obsidian Tower is the bulwark of the blood god, and as its name suggests from the outside it is a tower, impossibly tall, made of what looks like black translucent stone. From the moment one enters the tower however, it becomes clear that it is no building. From the outside it seems to be perhaps 200 yards in diameter, but beyond the main gate is a seemingly endless main hall taller than the most ancient dragon and stretching off seemingly forever. The inside of the tower is, in truth, infinite. Above the ground floor there are some six thousand or so levels, each finite and each smaller than the last by a tiny fraction. Below the ground floor there exists an endless labyrinth consisting of layer upon layer of tortured stone. All throughout the realm of the blood god stalk creatures more dangerous and vile than anything seen on the prime material. Twisted manifestations of his dark will peer out from every archway. The architecture of the tower itself would be sweeping and beautiful, but is subtly disturbing. The higher or lower in the tower one progresses the more pronounced and disturbing the architecture becomes.

The realm of Lord Vel is anathema to life. Every round a mortal being spends within the tower they must make a will save. The DC of this save is 10 plus the number of previous saves. Each time a save is failed there is a 5% chance the character will immediately die, a 5% chance the character will become possessed by some dark force (DM’s discretion), and a 5% chance that a devil or daemon (DM’s choice) will burst forth from the character’s head killing them and attempting to kill their party. The spell Planar Adaptation, and similar effects that inure one to planar forces do not prevent the will saves, but will prevent any failed saves from having an effect: You can tarry in the tower with such a spell, but its hold over you grows all the same. Sleeping within the tower is completely impossible, as the gaping maw of The Hungering Dark stares into your soul, and though the substance of the tower masks it from your waking sight, in sleep it is laid bare before you.

The use of a Wish or Miracle spell allows a single character to persist within the tower free of will saves for a single visit. Sleep becomes possible, though still quite disturbing, and there is no risk of death or possession, but the prescience of such shielding causes characters to shed a kind of mental light. Denizens of the tower cannot pinpoint characters based on this phenomenon, but they will immediately become aware if any such character is within 30 feet of them. The Wish or Miracle may be cast as long in advance as desired, but affects only one visit. If you leave the tower for any reason the effect ends and a new spell is required to safely return.