The Rogue Artificer Archer is very strong (Game Set Difficulty: Hard)
Here is my strategy;
First off Some stats, my archer is 21, has a 54% chance to critical strike, and 68 Dexterity. I also use a epic ring that gives 20% increased critical strike bonus damage and my second ring increases long shot damage by 30%. I also use a fairly normal 183 Damage crafted bow.
"Long Shot" when used properly at max range does 4000+ damage critical and will pass through others dealing 4000+ damage..
"Poison Weapons" (Damage Boost) Paired with "Explosive shot" = "Poison Explosion". (I often use this with Solas Vortex ability that sucks everyone in.). The end result is explosive shot with second talent will do max damage and everyone one will be poisoned.
"Opportunity Knocks" This ability states that when an ally scores a critical strike your cooldowns will refresh .5 secs quicker. However I'm 90% sure this works form your critical strikes to.
^ I believe this to be true based on instances where it seemed to work for me. An example, When I use leaping shot, it fires 12 Arrows. I have a 54% chance to critical strike, After leaping shot most of my cooldowns are reset, I can keep "Fallback plan" up 75% of the time due to this and spam leaping shot pretty much one after another cause the cooldowns reset after each use (except fallback plan because it has a fairly long cooldown).
How do I keep my stamina up? "Looked Like it Hurt", After each critical strike you regenerate 10 Stamina. Remember my 54% critical strike chance? Firing 12 arrows at once with "Leaping Shot" that's going to be a lot of stamina.
I also use stealth to drop threat, but not being assassin that's pretty much all it does, drop threat.
I don't use full draw, It's only better than long shot against undamaged enemies. Instead I just used the point in sabotage. I use one of the traps since you have to spec to them to get the additional critical strike anyway, I normally use spike trap for the knock down, then I just hop into stealth since my cooldowns reset so quickly.
I use Hail of Arrows, it makes "leaping shot" insane. You end up firing 24 or 36 arrows at once and don't forget those quick cooldowns, and "Looked like it Hurt" You mine as well have an automatic shotgun.
My role in the group is to protect the support (Solas) because the support keeps the tank (Blackwall) alive and the tank keeps them off everyone. I do all this crazy damage, but I die in 1-4 hits (Enemy Rogues will sometimes get the jump on me coming out of stealth, if I don't have a trap down). "Fallback Plan" is my heal. I don't really have a need for a fourth party member, but if you can stand being in a group with Vivienne she's a good choice for extra barriers and resurrects.I use Dorian the always dying mage because Vivienne is rude.
You will die quickly if you don't utilize fallback plan correctly, but that just makes it more fun, knowing you could of done something differently to survive.
If you decide to try the Artificer Archer after reading this I hope you have fun!
P.S. *****WARNING/IMPORTANT!: If I use hail of arrows when fighting a high dragon the game will crash. It is just too much damage to quickly, I could literally kill high dragons on hard in less than 30 seconds, however the damage is just too much too fast. As many of you know the dragon goes through phases during a fight and if you kill them to quickly the phase doesn't trigger correctly. On that note, only use hail of arrows during the final phase.*****