Recently a situation occurred in D&D 5e that the player handbook did not cover. I searched for examples or rules that related to the situation but was unable to find any that went beyond D&D's rules for traversing difficult terrain.
The situation in question — A large creature is intent on killing my PC and beside us there is a steep slope, I choose to run down the slope to try and escape while the creature follows. The agreement was made with the DM that because we were both moving as fast as possible down the slope we would roll to see if we would make it safely to the bottom or trip/slip and tumble to the bottom ending in prone position, receiving damage calculated in relation to the distance still to travel to the bottom of the slope and the AC of the entity that fell.
While I believe in that instance the DM acted suitably, can anyone provide any rules or documentation that covers this scenario for D&D 5e ?