In previous editions of Dungeons and Dragons there was typically a reasonable assurance of being able to resist/avoid forced movement, or a way to prevent being harshly penalized for it (saving throw to drop prone rather than going over a cliff in 4e).
In 5e while the number of ways to move enemies around has been reduced from 4e it is still very much present. The Warlock's repelling blast being the best example in that all it requires is a hit to push an enemy 10', which is positively deadly near a cliff side. Are there any rules I am missing for this? Obviously it isn't balance critical as it is terrain specific, and honestly the idea behind it is likely to be seen as fun by most players.
Still it seems very out of place from a numbers perspective in 5e. With typically lower monster HP's and party damage outputs, and falling damage remaining the same the cliffs have already become deadlier. Even simple environmental damage from some spikes is far more valuable to combat than it used to be. So while I am willing to accept there is nothing to do once an ability has moved someone into a dangerous spot besides watching them suffer, I feel like I might just be missing a rule somewhere.
Best Answer
It's out of place in 4e, but 5e is a different game and it's not out of place in any way. You're not missing a rule, just importing expectations into the game that aren't part of it.
To avoid being pushed off cliffs or onto spikes in 5e, you do what people do: stay far away from cliff edges, pits full of impaling spikes, and other lethal hazards. Adventurers will often choose to forego common peasant wisdom, but that is the price of adventure and a chance at fabulous treasure. Nobody said adventuring was a safe occupation.