Grasping Fog
A massive fog bank filled with grasping spectral hands rapidly claws its way towards the adventurers, forcing them to either quickly flee or be gripped by the encroaching fog.
Fly Away. The use of natural flight, or fly and similar magic (except levitate ) triggers a success for that adventurer.
Hazy Vision. The maximum range of any sight-based senses is 60 feet. In addition, Perception checks are made with disadvantage , and all passive scores (including passive Perception) are reduced by 5.
The adventurers can simply keep ahead of the grasping fog outrunning it with an Acrobatics or Athletics check. They might also seek out higher ground with a Survival check and wait for the grasping fog to pass.
Critical Failure. The adventurers are enveloped by the fog and dragged away, where they are tossed around like playthings and their belongings are rifled through. Each party member suffers a level of fatigue and loses 3 (1d6) Supply , if they were carrying any.
Failure. The fog tears at the adventurer’s gear, rending supplies—and something more precious. The party loses 2 (1d4) Supply and a randomly chosen a magic item carried by one of the adventurers is caught by the fog, snatched away as the mists recede. This magic item can be recovered in place of a boon or discovery the party would have obtained in the same region. It can be also recovered if the party spends 6 (1d12) hours searching for it.
Success. The adventurers avoid the fog without further incident.
Critical Success. Either by spotting their goal from the higher vantage point or happening upon a faster route in their rapid flight, the adventurers find themselves considerably farther than anticipated and have shaved 3 (1d6) hours off their journey.