Manbearcat
Legend
But in 5th edition we aren't talking about something that is outside the rules, that is all a part of the rules.
I'm not talking about changing Necrotic to Fire types of changes. Straight up changing a power can have serious implications in 4th edition.
All you need in 5th edition is Imagination + Ability Scores to do what you want to do. That is the way the game was designed. If I want to flip over a rail, grab a chandelier and come down on an enemy with my sword; all I need is to roll a Dex check first followed by my attack roll. 4th edition has a hard coded way of handling things because it was specifically designed with the grid in mind while 5th edition was not. Theatre of the Mind gives you a lot more freedom than grid based.
What happens in 4e if you attempt an action that you don't have a power that you can specifically attemp, the same thing that happens in 5e. Except in 4e you have better guidelines for improvisation so it is actually easier to improvise certain actions.
If you don't allow players to improvise, at least in 4e they will have significantly more options on a round by round basis than in 5e, where martial characters are limited to repeating the same basic attack over and over.
This is certainly the red-herring of the conversation because the truth is that it all totally depends on the DM. It's not like 5e all of a sudden introduced something that didn't exist before in RPG's. Nothing in 4e prevented you from using Imagination + Something Else either. In essence, the base of the systems is the same.
In both systems this is an ad-hoc ruling, but 5e gives the DM precious little to guide how to consistently make that ruling. In addition, in 5e it is always a DM ruling with variable certainty.
Agreed with Ashkelon and D'karr here. The core rules for stunting in 4e couldn't be more transparent and codified.
Want to do an Indiana Jones vine/whip across the chasm or a swashbuckley swing from the chandelier across the common room? Cool. Move Action. Roll Athletics Medium DC. Success? You move from the starting square to the end point along the rope/whip (etc) path. Failure? Either you're still at the starting point or maybe you make it across but you give up CA UtEoYNT. Want to not provoke OAs? Hard DC.
Want to shoot a stalagmite down on a group of enemies in a cavern? Cool. Limited Use Standard Action. Roll Dungeoneering Medium DC. Success? Ranged Burst 1 centered on point below stalagmite. Medium Damage Expression. Level + 3 vs Reflex attack. Miss: half damage. Difficult Terrain for the duration of the encounter.
This is trivially easy and core, p42 stunting rules in 4e. The terrain powers are littered with examples of this.
You could certainly do this as well in 5e. It is just that you're required to perform the necessary mental overhead on the spot and deal with the table handling time of negotiation/adjudication of effects (math and balance considerations) and DCs rather than having systemitized, robust stunting infrastructure (with a vast array of mechanical exemplars of such genre tropes at your disposal).