With the advent of 4th edition we may now be seeing a true balance in the D&D game this leads directly towards improved possibilities for diceless play. (imbalances are far more obvious in the context of diceless play.)
To quote the players handbook.... "The actions in a combat encounter happen almost simultaneously in the game world"
Bringing this truly into the actual turn sequence we can add a simultaneous revealment of preselected "attack powers", these can manifest in the form of key word based "strategic" variants. Easy to do for the basic melee and ranged attacks. Other specialty attacks may be defined as always employing one or two of the key words
Lets call these keywords Normal, Guided, Deceptive
Normal Attacks operate well like a normal take 10 on your performance
Guided Attacks have there benefit inverted when confront by deceptive opposition, and should be markedly superior than a Normal non modified version in one version or another.
"Defend and strike" might be a guided effect which improves it users defense by 4 and reduces damage taken by 2 (but which becomes a reduction of a defense against a deceptive attack).
"Aimed Strike" variant would also have the guided attack and improve its attack action by 4 and increases damage dealt by 2 (or be reduced by 4 and damage reduced by 2 when opposed by a deceptive action on there opponents part.)
Deceptive
"Feint and Strike" though inferior in damage to a Normal Attack reduce by 2 it inverses the advantages of an opposed guided actions (essentially by presenting false openings and hard to follow or indirect attacks).
"Complex Combination" actions are harder to implement, -2 on your attack and figure out same base damage as the normal attack and also inverse the advantages of an opposed Guided Attack.
Note in the current D&D 4e to do deceptive attacks requires the application of a separate skill Bluff...and are not common even for opponents inclined to use them...ie "Once per encounter, you can try to gain combat advantage against a target by making a Bluff check" - ie a +2 on your attack. This is not adequate or realistic feints are about as frequent as parries for good reason. With this non-transitive model roughly one third of your adversaries attacks include deception as a primary factor or complexity which requires figuring out... and contribute significantly to your attack -- this strategic out guessing your opponent is part of the d20 itself... it is not a tacked on modifier so we could still keep the bluff check to represent a more extreme than normal deception.
Modifier cards
Play these cards face down when you are attacked or making an attack against an opponent they define the keyword now associated with your attack or if not making an attack against an opponent your defense. Basic attacks can have any modifiers others may have limits ...
Additional Key Words
Another couple of key words are actually quite possible Predictive and Instinctive , represent attacks and defenses who are more completely unplanned or which look beyond normal deception
You can decide how patient or rushed or how much you are paying attention to defense while performing actions.
Taking X
The following rules in some sense take the place of the standard rules of taking 10, These rules even work in a combat context and to that extent replace certain feats and combat options they do offer more options to every combatant and in general more choices about how long you take attempting an action.
Basic Action Performance : focus + skill + associated attribute +/- time effects + the impact of luck.
non combat actions difficulties generally assume full focus while combat actions assume split focus
Taking Focus up to +5 / Focusing on Defense down to -5
Focusing completely on "action" can imporove it considerably but reduces your armor class by 1 for each point spent in this way. Note this applies to attacking an opponent as well as general skills.. Outside of combat taking focus is very nearly the norm it makes you highly vulnerable to being interupted.
Focusing on defense has the opposite effect reduces the performance quality by 1 and increases defense by 1 per point.
Taking Extra Time up to +5 / Rushing It down to -5
Can add 1 to 5 from your performance
Rushing your performance can subtract 1 to 5 from your performance quality.
In combat choosing these options may result in a gain in number of attacks during a round or if both characters rush or take there time this may result in simply "shorter" or "longer" combat rounds
Careful, Neutral, and Bold
A character may reduce the impact of chance on their performance by choosing the tried and true methods by paying closer attention to the basics etc. In game terms the player choosing this option for his character can have a definite game effect basically to increase or decrease the luck cost on modifying the actions performance quality (note the basics are easier and you know them better but they pass up opportunity for quality in the result). One can also increase the impact of luck on an actions performance essentially they up the potential for reward by doing more improvising and using some tricks which potential for more extreme results remember you do not know these tricks as well.