Level 24 or 25 is easily doable, 24 at a minimum. I'm not sure how much content you'd have to skip to only hit 21 or 22 in a play through but that's certainly not typical for me. If it's typical for you then you'll have to adjust the numbers down by 2-4 levels of cunning.
You have to do EVERYTHING to get to that level, and you probably need the help of a lot of DLC content that not everyone has. Whether you or I end our games at level 24 is irrelevant. Most people end the game around level 21 or 22; I guarantee it. And when I talk about builds, I am aiming it towards what is most effective for most players. In this case, your build gains relatively speaking the higher the level because you gain cunning (thus making Song of Courage better), and I simply gain attack and defense that might be overkill anyways by that point. So talking about it at level 24 is just giving your build an advantage, when that is not a realistic level for 95% of players. It's not a big deal though.
Strength: ~15 (i.e. base)
Dexterity: 30 before gear
Cunning: 86 before gear (assuming level 24 and both stat books)
We start with a set of +cunning and +all stats gear to buff cunning as much as possible
Cunning Gear:
Helm of Honnleath 2
Andruil's Blessing 2
Dusk ring 3
Key to the City 2
Dead Thaig Shanker 5
cunning from gear 14
Total cunning for Song of Courage prebuff: 100
Total crit from Song of Courage: 12.0%
With duncan's sword this could be as high as 106 but that's only really possible really late game after you pick up the imperial ring. One could also be level 25 but that requires the use of questionable tactics like killing NPC allies for XP or using repeatable XP turnins. Things many would consider exploits. It's only .6% crit so I'll leave it out.
Now, after activating Song of Courage, we swap gear-sets for one that adds as much crit as possible.
Critical gear:
The Long Sight: 5%
Cadash Stompers: 2%
Longbowman's Belt: 2%
Far Song: 3% (could have used whitewood but damage would have been much worse)
Total Crit from gear: 12%
We're now at 12% from gear and 12% from Song of Courage with another 1.6% from the tier 7 bow that won't count for aim. Now we add party member buffs.
Party (just for Aim buffing, could switch to anything afterward):
Leliana Bard @ 60 cunning: 8%
Zevran Bard @ 60 cunning: 8%
Shale with ranged aura: 10%
Also keep in mind here that song buffs of more than 8% from either bard are possible as 60 cunning is pretty low. Remember we could be using all of the +cunning equipment we used in step one on our PC archer to buff the songs of these party members as well.
Total Pre-Aim Crit: 10% + 8% + 8% + 12% + 12% + 1.6%= 50.0% + 1.6% from bow's base
Total Post- Aim Crit: 101.6%
Now if we remove every party member and every piece of +crit equipment aim is adding 50% crit by itself. Once active Aim will remain active at this buffed level until deactivated by switching weapons, including to other bows, or switching to another bow sustain stance like defensive fire or rapid fire. This means any gear can then be equiped including Felon's Coat for 6 dexterity, Key to the City for 2 dexterity, and Cadash Stompers for another 2 dexterity for a total of 40, although this could also be higher if we really wanted it to be.
This is essentially just an exploit of the game. You aren’t meant to do things like put on +cunning gear for Song of Courage maximization, then take it off, put on crit gear for aim maximization, and then take it off and actually use the best equipment after that, while keeping the bonuses from the previous sets of equipment. That just exploits the fact that sustained spells and abilities do not do any check for your stats after you turn them on. It’s not something that the devs meant you to do; I guarantee it. If your build is only competitive with mine because of this kind of exploitation of holes in the game’s rules, then it is NOT competitive with mine. That’s not even mentioning the fact that doing that kind of shuffling of equipment is just annoying.
Party (just for Aim buffing, could switch to anything afterward):
Leliana Bard @ 60 cunning: 8%
Zevran Bard @ 60 cunning: 8%
Shale with ranged aura: 10%[
Again, this is just a blatant exploit. You shouldn’t get any bonuses from Leliana’s Song of Courage when she is NOT there! I know you CAN do it and it’s a single player game so you can do whatever you want, but you cant say your build is better because you can exploit rules in the game to vastly increase the power of your build. If you want the buffing from those party members, you should have to bring those party members around. And if, in order to make your build better, you want your party to be a rogue archer PC, Leliana, Zevran, and Shale, then be my guest, because that is a very badly balanced party that my build wouldn’t have to use.
Could you do this trick without a cunning based build? Yes, of course you could. Is it better? I don't know. I know the crit addition from song of courage would be smaller. Base cunning is around 15, no? After gear and fade essences that's maybe 35 I think? That would be 5.5% crit with the Song, a loss of 6.5% party wide, 13% personally. Is this worse in terms of DPS? That would depend on how much the party gets out of that crit, what the defense of the target is, what the party brings in terms of attack buff and defensive debuffs, and target armor rating I think.
With two mages in the party (which is probably optimal, lets be honest), your Song of Courage will only help one other character in your party (except in bizarre situations like Virulent Walking Bomb being able to crit), limiting its extra usefulness.
In any case, a loss of 13% crit rate really is only a loss of 6.5% damage (About 7.1% if you have Far Song). That’s not a lot in the grand scheme of things, especially when my build will have about 33 higher attack and 66 higher defense than yours at level 24. 7% extra damage pales in comparison to 33 higher attack (not to mention the defense, which makes my archer into a tank while yours needs to be managed so as not to draw any agro because you have bad defense, armor, and hp).
I already calculated all of this out for you earlier. I assumed you had 85 cunning, and I had 20 (meaning no extra gear for either of us. The extra cunning gear would basically be a wash anyways). I gave you an 80% hit rate, which is generous for a build that has no extra dexterity beyond the necessary 30. Remember, arrows naturally hit a MUCH lower percent of the time than melee even with the same attack rating because any enemy with a shield has higher missile deflection than defense and there are many shielded enemies. Furthermore, many shielded enemies use shield wall/cover/defense, which further boosts missile deflection beyond what the shield does. Lastly, archers can’t flank, something which significantly increases melee hit rates. You NEED high attack to get a high hit rate with archery, and your build won’t have that. I gave you your high crit rate. I factored in armor penetration from cunning, and even assumed that the entire extra armor penetration applied 100% of the time, which is not realistic at all. My build still came out a decent bit ahead in damage.
I didn’t even need to factor in my monstrously higher defense. I didn’t need to factor in the fact that rogue archers can go quickly in and out of stealth to get a free crit every 10 seconds anyways which devalues your higher crit rate from cunning since it won’t have an effect on the 20% of your shots which would be done from stealth. I didn’t mention the fact that use of the Critical Shot talent similarly negates the value of your extra crit rate. I didn’t mention the fact that your build will miss on Arrow of Slaying a significant amount of times, especially before you get Master Archer, while mine will hit as close to 100% of the time as possible. I assumed my archer would use a gimped version of Song of Courage, instead of pointing out that my character would be free to go Ranger instead for a boost in DPS that crushes your build. There are SO many things like this that I didn’t even have to get into to prove my build was better.
I'd like to stress again the point that, if you include stuns which remove significant portions of defense on their on, there are quite a few defense reduction talents and items available in the game. The tank alone will have 4 stuns and, most likely, warcry for -10 defense and that's just by themselves.
Warcry decreases enemies’ attack , not their defense.
Anyways, sure, stuns will help you actually hit some, but the fact is this. Your base attack will be abysmal. You will NEED to have Song of Courage, Aim, and Dueling on to have a decent to hit. First off, you’ll need to be pretty far on in the game to get all three of those (since you need two specializations for it). Thus, youll spend the majority of the game missing A LOT. Secondly, its orange and yellow enemies that are the real problems most of the time. Those enemies are gonna shrug off stuns pretty quickly, and they will frequently have very high defense, especially shielded ones. You will have a very tough time hitting them even if youre buffed up with sustainables, because youll have a tough time getting to like 130 in attack.
Lastly, it should be mentioned that your cunning build pidgeonholes you into using Longbows. They are the best option anyways unmodded, but if one has the dex hotfix, this gimps your build. You can’t use shortbows since you need the +10 attack and crit bonuses from Far Song, AND you NEED damage to be affected by cunning. However, with the dex hotfix, shortbows are the best bows in the game. Having a 1.0 modifier from dex for damage instead of a 0.5 modifier from dex and a 0.5 modifier from strength/cunning is much better. The damage potential is SIGNIFICANTLY higher (as in, I’ll have like a 30% higher base damage AND the much higher attack rating).
You speak a lot about fairness but keep pulling Leliana's numbers from above as if they were PC numbers. They aren't. A PC archer with a min/maxed party would fair better than a 70% hit rate, far better. In fact most of your 'extremely generous toward cunning' numbers look pretty weak to me. Relative to what a full fledged build is capable of 85 cunning is an decent base but certainly not a generous total after gear bonuses, which are significant.
Why does it being Leliana really make that big of a difference? A cunning-based Leliana build would have the same dex as a PC build because the goal would be 30 either way. The difference would just be that the lack of Fade essences would leave Leliana with less cunning, but that doesn’t affect hit rate. She would be a Bard/Duelist as well, so she’d have the same sustainables. She might occasionally be a level behind you, but that’s not a huge deal. The only other thing I can think of is that you are saying this because you assume the PC would be geared up with uber gear, while Leliana wouldn’t. This is probably true, but its not a HUGE difference. Far Song will give +10 attack, but many people get that one for Leliana anyways. Otherwise, things like Felon’s Coat and Andruil’s give +2 or +3 overall attack bonuses.
I will tell you one thing. I just looked at my first playthrough around level 18 (I happened to have a save with Leliana in the party from then). I specced Leliana with a random half cunning-based build where she ended up with 20 strength, and 46 dexterity (ie much higher base attack rating than your build would have) at that point in the game. She had Dueling. My PC was a cunning based rogue, who had gotten Song of Courage so she had been being buffed by a good song of courage for a bit. I also had her using Aim consistently from midgame on. She had on typical second-rate gear you’d give an NPC, so there was a bit of increase to her dexterity. Her hit rate for the game was 65%! Sure, this was at level 18, was her hit rate for the entire game, and she had lesser equipment than a PC would have, but her base attack was 10 higher than your build’s! That basically makes up for the fact that her equipment was lesser. It was still 65%! Obviously a level 24 character would hit much better than the average of a level 18 character’s game, but the point is that assuming 80% with Song of Courage is not unfair. And furthermore, the other point is that your build would CLEARLY have serious problems hitting throughout the entire game even if you think you can get your hit rate up okay by the end.
Crit damage is not limited at 50% extra damage. Items like Red Jenny Seekers and Far Song add to this multiplier, on an archer it's entirely possible to get critical hits up to 90% in the right gear although since massive armor is impractical I usually just use Red Jenny Seekers and Far Song for 75% myself.
Fair enough, but that doesn’t really change things that much. You said yourself that my build would crit 13% less with Aim on. That means you have an increase of 9.75% damage instead of 6.5%.
Personally I don't consider defense even remotely useful on a party based build. I run with tanks 100% of the time and I don't have any trouble with deaths. If you find defense useful then adjust your stat weightings accordingly, were I to place a non zero value on defense I'd readily agree dexterity to be a superior build in all cases. It's also better early in the game but I build most of my characters to their fullest potential by level 24 and no earlier. Again, you might have different priorities than I in this reguard. I'd certainly concede a dexterity stacking build has an easier time leveling up and dealing damage in the mid levels than any other build for both warriors and rogues.
Why would you focus on how powerful your builds are at level 24 solely? You spend virtually no time at level 24. I guess its being a powergamer, but I think a power gamer should consider the power of their character throughout the game.
And you may run with tanks etc etc. But there are two problems. First off, that pidgeonholes you into needing a good tank with taunt at any given time. That is somewhat limiting, even if having a dedicated tank is normally a good idea anyways. Secondly, you clearly don’t use Scattershot that much. It gives you huge aggro. I realize you can use a taunt afterwards, but that can be impossible if taunt is on cooldown or your tank is down. You may say your tank never goes down, but at that point you’re just saying that your build is really good because youre a really good player who makes no mistakes and thus never has your archer attacked. That doesn’t mean your build is better; it just means a good player can deal with the glaring flaws in it.
Lastly, you can’t reliably solo with your build. Mine, you can.
Again, you don't have to tailor anything for the archer. All the crit buffing is done ahead of time and the party could then be switched to anything. Aim can be offset with salves and there is a cap on attack speed. A party will have defense debuffs no matter what really so there's no loss there. Even if it was an acher was with three mages imagine how easy it would be to shatter frozen targets with a 50%+ chance to shatter with every auto attack. No wasting stamina or mana on auto crits is nice.
I will ignore the fact that your strategy here is exploitation of flaws in the game. Beyond that, I’d like to discuss Aim. You advocate the use of salves. That’s all well and good, but that brings in a whole new variable. You won’t have unlimited salves, and what you do have will cost you money to buy the ingredients for. You cant ignore that cost.
The fact is that Aim doubles crit rate because it also essentially doubles attack time. As far as I know, it adds 1.5 seconds to attack time (not aim time, so it can’t be negated with rapid fire). Base attack time for a longbow or shortbow is 1.65 seconds. So Aim almost doubles it. Thus, without boosting your character with extraneous items, the doubling of the crit rate doesn’t do much more than ensure that you get the same number of crits per second as before.
You can talk about Haste all you want, but the fact is that Haste doesn’t work on archers. Your swift salves may work (I don’t actually know), but again as far as I know, you cant have unlimited swift salves, so this is a rather silly point to hinge your idea on.