Woe Betide the Cairn-on-the-Mount

 ACT I: HUNT

REASONS TO HUNT THE BEAST

1 There's a bounty on its head, and you need a(nother) castle

2 Its blood is said to have properties of a necessary potion

3 It came into town and killed the bishop's daughter on the chapel steps

4 The hunters are out of prey, and the village will starve

5 There's a treasure map in its stomach

6 A local oracle foretells disaster in the world's signs just as the Beast is sighted outside town

ENVIRONMENTAL HAZARDS

1 Thick fog

2 Driving rain

3 Intense wind

4 Difficult terrain

5 Extreme temperature

6 Roll twice, this can stack

BEAST ABILITIES (Roll once per party Level)

1 Flight

2 Incorporeality

3 Immunity to metal 

4 Spits fire

5 Splits like an ooze

6 Immune to Rune Magic (Arcane, if you're boring)

7 Immune to Blood Magic (Divine, if you're boring)

8 Size change

9 Gelid blood- if you are near it while it bleeds, you slowly freeze

10 Surprise, motherfucker; it can cast spells like a wizard

In addition to these abilities, when the Beast is reduced to a state where one more blow may kill it, it opens its eye. Choose one CLOSE person- they get a disease known only as "Rot". Rot occupies 2^(full days with Rot) DEX slots, and incurs an equivalent penalty to all STR, CON, and WIS rolls. When Rot occupies every DEX slot, it kills the host. Necrotized black flesh spreads outwards from the host's eye day by day until it consumes their body and they crumble to ash.

ACT II: CONDEMNATION

"That's... puzzling. Ever since you've returned from destroying the Beast, we have not felt the presence of the Great Mother. As such, our clerics cannot heal your Rot, and the nearest other ones are days away at least. Your only hope is going to the Cairn-upon-the-Mount, the home of the Great Mother. Perhaps you may appease her yet, and your companion's Rot be cured."

ACT III: PILGRIMAGE

• OFFERINGS
• The villagers tread no further than this room to bestow their sacrifices
• What do they give as an offering to the Great Mother?
• How much of it was left as unsatisfying, and how much has been dragged away?
• CRYPT
• The Cairn was built by the antediluvian indigenous peoples of this realm
• Who are they, and which of them are buried in this room?
• What was the guardian they entrusted to keep their bodies intact?
• GATE
• The builders experimented with ripping holes in reality and opening gateways to other realms
• Where does this latent gateway lead?
• How do you open it?
• GAUNTLET
• The offerings from the entry chamber are dragged through here to the final room
• What overwrought trap occupies this room?
• Why is the Beast lineage impervious to its effects?
• MOTHER
• The Beast's wrathful mother slumbers in grief (roll for 2 extra Beast Abilities)
• How does she grant the village folk their divine power?
• How can you appease her and set things right?
• SANCTUM
• The original builders wanted to hide this chamber, where they secreted their most valuable treasure
• What was so valuable to them as to be hidden in this room?
• Who is looking for it today, and how close are they to getting it?