Pristine white snow hides a multitude of hazards underneath its surface.
Realize Danger. With a Nature check an adventurer knows how to stay safe in the tundra and the party has advantage on Athletics checks made against it.
Tundra Troubles. At the end of every hour they travel, the Narrator rolls 1d4 for each adventurer to see if they run into a hazard in this terrain. On a result of 4, roll again and refer to Table: Tundra Trouble to determine what assails them.
A group check can be made to overcome this challenge, including Athletics checks to quickly march through the snow or Survival checks to find paths that minimize exposure to crosswinds.
Critical Failure: The party takes 2 days to get across the tundra. Any adventurer that takes 20 or more cold damage suffers a level of fatigue .
Failure: The party loses 1 day of travel time getting across the tundra and each adventurer loses 4 (1d4+2) Supply.
Success: The adventurers cross the tundra in half a day’s travel.
Critical Success: The adventurers cross the tundra in just half a day, and they see something interesting amongst the snow and ice. Roll on the Boons and Discoveries table.
Table: Tundra Troubles (1d4)
1 Biting Cold. A blustering tempest of freezing gales roils through. At the end of every hour spent traveling through this area, a creature makes a Constitution saving throw (DC 5 + 2 per previous save) or it takes 3 (1d6) cold damage.
2 Reduced Visibility. Vast amounts of snow drop down from the sky. For the next hour, the maximum range of any sight-based senses is 10 feet. In addition, Perception checks are made with disadvantage , and all passive scores (including passive Perception) are reduced by 5.
3 Shifting Ice. The ground beneath suddenly cracks and gives way, revealing that it was ice! The adventurer makes a DC 17 Dexterity saving throw or they fall into freezing water, taking 11 (2d10) cold damage. While submerged in the freezing water the adventurer takes 11 (2d10) cold damage at the end of each of its turns. Any creature that attempts to pull the adventurer out with a DC 17 Strength check also makes a DC 15 Dexterity saving throw, taking 5 (1d10) cold damage on a failure.
4 Predator. A creature (of a CR equal to twice the party’s average level) that is native to the area spots the party and tracks them, waiting for the next Tundra Trouble hazard before it attacks.