Wrong Warp

This event may occur when the party uses one of the portals belonging to the overworld network. The event triggers when the DM rolls a 20 on a d20. Each time the portals are used, the required roll is reduced by 1.
When utilizing the teleporters of the overworld network, the party finds itself transported to a different destination than they intended. A bright light hits their eyes as they land in the middle of a barren, pale purple desert. The sky is no longer covered by clouds, instead, a clear blue sky meets them. They have found themselves transported to the sleeping wastes, the part of The Ashlands south of Meydia. So far away are they from the province that they cannot even spot the eternal blanket of clouds that covers the land nor the high mountains surrounding it.
The party will have to cross the smoldering desert to return to Meydia. The journey to Meydia will take several days, as the adventurers must cross 45 miles of the unforgiving terrain. The speed at which they travel is determined by a collective Wisdom(survival) check. Each player will perform the check at the start of the day, then the average of the lowest and 2 highest will be taken to determine the distance traveled. The party may either take their time traveling, reducing their exhaustion, or push through the desert. If the party takes their time, the distance traveled each day is the previous survival average devided by 3. If they hurry, this average is instead devided by 2.
As the party travels through the smoldering desert, they will become exhausted over time. At the end of the day, they must make a Constitution saving throw to avoid gaining a stack of exhaustion. The DC of this roll starts at 7, increased each subsequent day they travel by 4. If a player failed their previous Constitution saving throw to avoid getting exhausted this way, the DC will not be decreased by 3 instead and subsequent base increases of the DC are halved. If the party rushes their journey, each of them has disadvantage on the Constitution saving throw. The DC may be increased or decreased based on other factors. For example, not eating or drinking on a day increases the DC by 2 and drinking fresh water decreases the DC by 2 at most once every two days. The stacks of exhaustian gained from the journy cannot be removed by resting due to the extreme cold of the desert at night and lack of cover. If the players can, somehow manage to get proper cover, they may make a Constitution roll to determine if they get enough rest to loose their exhaustion. The DC for this check is based on how good their cover is.
On the last day, when the travelers will be able to reach, they will be attacked by Macra the Desert Lurker. Inspecting the ruin at the center of the battle map allows the players to find a hidden compartment that contains the Jester's Prism.