[PTTG]

Inward:

It is said that in the Hall that is the Heart of the World, there is a once-great Emperor. His name has long been lost, but his hubris lingers. He was granted three wishes, and so asked for himself to outlive his castle, his castle to stand after his city had fallen, and his city to last forever.

Perhaps apocryphal. But what is known is that as one grows closer to that terrible city, the arrow of time flies more slowly. It is a sweeping and subtle thing, most likely the work of the gods. From the perspective of the traveler, day and night, heartbeats, the seasons -- they move normally. But one could easily travel away for weeks and return to find that years have passed at home. It is said that should an assassin visit death upon that king, the spell will be broken. None have yet returned from such a quest.

Outward:
They call the mountain the Hearth of the Gods. It is the primordial source of all motion, all matter, all heat. The lands around it are scorching black deserts dotted with sand-weathered obsidian monoliths, a badlands which forbids entrance to the God's domain. As one moves further, the climate cools, but that is merely a side effect of the nature of the Hearth. Time only flows in proportion to your nearness to that volcano. Adventures to the inner jungles may take years, but the traveler returns to find only weeks have passed.