Elda King said:
The line between concept and mechanic is not clear, the rules are
This doesn't make sense to me because the rules are mechanics, and yes, they are quite clear. The "concept"/"color"/"story"/"fluff" of 4e powers is clearly much more nebulous than the "mechanic"/"rule"/"crunch" is.
You can improvise, make new rules, change the rules as much as you did in any other edition; most "stunts" weren't covered in the rules in any edition, after all.
I'm pretty sure characters in every edition of the game swung from chandeliers and knocked over braziers and did other nifty things. 4e has a codified system for it in the context of combat (the stunt system), 3e had an underpinning of rules detail that could handle anything in context, 2e and previous editions pretty much left it up to nebulous "dm judgment," but it I'm reasonably confident it did happen.
4e's razor-balance on the powers, however, makes it a little bit wonkier if you hope to preserve that balance. If you allow powers a greater deal of flexibility with 'stunts,' then you risk throwing this balance out of whack because, say, your warlock with the creative player becomes a better controller than your more casual, laid-back wizard player, and the net effect is that your wizard player isn't having as much fun. Or with the "limited damage expressions," your fighter becomes a better striker than the rogue, leading to much the same effect. This particular pitfall is fairly new in 4e, or at least particularly virulent.
About rationalizing: yes, that happens. And yes, one of the main proposals of the edition was "make it fun, not realistic".
Which is why it can be dangerous to ask 4e "Well, what can this conjured hand actually do?" The answer is right in the power: that's all that the hand can do, and it can do that fairly reliably. To give it other stuff it can do risks disturbing the careful balance that enables this "fun" (if it's not carefully watched).
If you want a system that's all about unrealistic fun and loves player creativity like stunts, take a look at Feng Shui. You can kill things and take their stuff just as easily there, but how you do it is basically by a more detailed version of 4e's stunt mechanic.

That's a system where it isn't dangerous to ask that question, and answer with whatever your imagination desires.
"these mechanics are things that you shouldn't generally mess with"... Why? I don't really see any reason for that.
Because of how carefully the powers are balanced, it is riskier to the fun to allow a lot of elaborate stunting with them. Adding or subtracting damage or an effect on any kind of a consistent basis threatens 4e's roles, 4e's damage-by-level formula, the question of choice between powers at any given level, and it doesn't end there.
Your wildly creative player may end up contributing more to the game than your more casual or strategic buddy, which, generally, isn't much of a desired effect. The stunt system as it exists now is to help that creative player feel awesome when they are creative without giving them too much of an edge. Elaborating on it much threatens to shift game balance away from the Math and to the stunt system.
This isn't necessarily negative, but does involve juggling fire.
Mudstrum_Ridcully said:
The only reason why you cannot knock an ooze prone in 3E is because it is explicitly written in the rules.
Actually, the reason you can't knock an ooze prone in 3e is the same reason you can't knock an ooze prone in any other edition before 4e: because puddles can't be knocked over. Because it doesn't make sense. The reason you
can knock an ooze prone in 4e is because 4e values consistency much more highly than any edition before it, so it is very important to 4e's structure that your power be fairly equally effective against a broad selection of enemies. Rationalize that however you want. The rules, here, trump common sense.
On the other hand we have rules saying that all undead are mindless and immune to mind-affecting powers, even Vampires that definitely have a mind. Is there a "color" reason for being unable to control vampires or liches (especially since there are spells like Control Undead that work against them)?
Again, this is grounded in what makes sense (from the designers' persepective, anyway). Mindless creatures of all stripes are immune to mind-affecting powers because they don't have minds to be affected (seems pretty explicit, in the same way that things without legs cannot be tripped). Undead are immune to mind-affecting powers regardless of mindlessness because of their alien needs and desires when compared to mortals (and yet can still be compelled by those who work closely with undead). Heck, this was part of earlier editions' "exception-based design." "Undead can't be charmed EXCEPT with this specific ability."
Heck, take a look at the widespread immunity to poison amongst undead in 4e for a legacy of this. Vampires have functioning circulatory system in 4e according to Open Grave, but poison still doesn't work because it makes sense for poison to not work on things that are walking corpses.
4e is sometimes very schizophrenic in what it chooses to be realistic about.
This is why the fluff text isn't a reliable indicator of what a power "should" be able to do, in a rules sense. When the fluff becomes gospel in 4e, it threatens to be a bull in a china shop, wrecking the place up a bit if it gets off balance.
The rules in 3E also don't tell us that you can use Bigbys Clenching Fist to manipulate a lever. You might allow that, but the description of the spell doesn't imply that you can use Bigbys Clenching Fist to do anything that a clenching fist could do.
And D&D 3E or 4E wouldn't be the only ones to do such things.
The rules in Shadowrun allow you to cast a Flamethrower spell. The spell doesn't describe how or if you could try to use this to lighten up a cigarette (and still be able to smoke it, and not it burning away). A generous DM might make a ruling and decide that it's okay to do that with that spell, even if it's usually a combat spell designed to kill enemies and burn stuff down.
Right, but none of that really qualifies as "stunting" like this thread is talking about, in terms of accomplishing some direct combat effect (a push or pull, a prone, cover, damage, whatever). I'm just mentioning that in 4e, the careful balance means that you need to be careful when adding effects to powers in a way that is fairly new, and that "it makes sense because of the color" isn't a comfortable underpinning in 4e, since there's a lot of situations where things that make sense because of the color are trumped by things that have to happen because of the rules.