KUPALA’S DEMESNE

Of the handful of demons bound into the earth itself, Kupala is the oldest and most powerful. In fact, Kupala was the first demon ever

to be bound in such a fashion, and he may even have invented the technique with the aid of his priests and followers.

No matter how the binding occurred, it allowed Kupala to anchor his essence into the soil of the Carpathian mountains, deep in the heart of what would become Transylvania.
Kupala inhabits not just a single mountain, but the entire range; his essence lies within every handful of soil in the coffins of those Tzimisce who worship him.

The demon lord’s “body” is so large that even he cannot keep track of everything within his boundaries. He can certainly sense large or significant events, and bring his powers to bear upon them, but individuals often escape his attention.
Even other demons can, upon occasion, pass through his border without being destroyed. Those demons and thralls who have survived such passage tell of a wilderness of brooding evil and darkness, where the constant presence of demonic power throbs in the soil like the beat of a giant and tainted heart. Within the region, power comes easily, and the energies of the demonic soul are always at hand — but that soul rages and snarls, barely controllable, lusting for destruction like a separate entity.
If mortal characters possessing demonic powers (i.e. thralls or demons with human hosts) enter Kupala’s boundaries, all Arcana rolls enjoy a –1 difficulty. Rolls to avoid gaining Torment are at +1 difficulty, however, making it harder for characters to control and withstand the horrors of their powers. With a Perception + Awareness roll (difficulty 8), characters can detect the presence of taint in the very
land they travel through. A subsequent Intelligence + Occult roll (difficulty 9) allows a character to realize just what those energies are, and what kind of place — what kind of being — they have entered. Hopefully they can escape before gaining Kupala’s attention; the elder demon has no love for any of his kind, and his worshippers are hungry for the taste of demonic blood.

Retirado de DEVIL'S DUE