Nice Guide there Ivory. I played with you the other day on my Fire/Dev blaster in RV (Crimson-Nite). Pwned us some Corrs, Doms and brutes (even a stone brute).
You didn't talk much about Epic powers though. I love ice mastery with my /Dev. The snow storm power is great and devastating especially in PvP. The webnade + snow storm combo = no movement unless the foe has Teleport. The Frozen armor adds a little more defense you what you get with Cloaking device and smoke nade (if you took it). And hibernate is a great way to get back to full health and end.
Force mastery is also great for PvP and PvE. PFF, Temp invul and FON are great damage mitigation powers.
If you are not into PvP, munition mastery can be nice. LRM rocket adds some more nice AOE damage for PvE. Also Body armor is a passive which is great if you want some damage resist but don't have end to spare for a toggle.
Fire mastery has some nice things (like a rez), but I don't think it works the best with /Dev.
I have to say, despite the complaints I've seen about the lethel damage resistance and lack of Buildup, I've also found this to be a great combo, and I haven't even gotten up to Rain of Arrows yet.
I've definitely been able to survive situations my fire/energy blaster friend hasn't, and my Ice/Ice blaster struggled with (at least at low levels) because of the combat control abilities of Devices. And thats enhanced by the fact that because I don't need Stamina, I can have even more utility powers; the Stimulant I could work in has kept me alive by keeping my team defender from getting mezzed, since very few have self mez protection. Plus it tends to put you first in line for buffs and heals. 
Not having to slot as much accuracy helps with the low level whiff-fest, helps at mid levels because you can use one DO Acc and 4-5 DO damages while you are slotting up, and helps at high levels because you can pack more recharge or End Red in by not needing the Acc slots. IMHO that substantially makes up for the "high lethal resists" of foes.
Its best if you have a tactical mindset, if you really just kind of want to run and shoot, this may not be the combo for you.
I'm having fun with a 9th Level Archery/Devices hero now, after a long absence from the game.
I saw a couple other archery guides that were written for I7 or I8. Have there been any changes since then that are particularly relevant to this power set?
I don't think Archery has changed much at all. For /Dev... only really two notable things I can think of. One, Smoke Grenade is now auto-hit in PvE for the -Perception Debuff (I think it has a to hit roll in PvP). The -Acc Debuff part of SG still has a to hit roll in Pve and PvP, I think. Second, Taser is now a ranged attack, only 20 ft, but its still something.
Any ideas on slotting for the Devices powers, particularly with regard to IO sets? I notice, for example, that it's possible to slot Caltrops with a set like Pacing of the Turtle... but would it make sense to do so, or just be a waste of slots?
Archery / Devices
There didnt seem to be a good guide for this power-set, so its time to fix that!
Archery / Devices is one of the strongest power-sets, not in raw toe to toe power but in potential and ability to change to your environment.
Good things: Low endurance, great accuracy, 2 sniper-level attacks, strongest re-usable AE in the game, corner shot abilities *more on this later*, +per from devices, stealth power, archery has low agro in terms of pulling monsters from groups (very stealthy power), in PVP archery is very stealthy (the enemy has a hard time telling where the attack came from to pinpoint you, keeping a low profile and letting you get away with more without making them target you).
Bad things: Long animation times, lethal is more commonly resisted, only one build-up ability
Archery uses mainly lethal damage, but with devices you can offset the instances where your arrows arent the best method. Being able to think ahead and read where your enemy will move is a key to being successful when relying on your devices side.
First, lets go over the nuts and bolts then we can talk about tactics.
Archery-
Snap Shot:
Damage- Minor
Recharge- Very fast
Range- 80 ft
Great ability, the fastest attack in terms of animation time. With the new invention system, you can slot this (and its big brother, aimed shot) with a wide range of nice benefits to pluck off in the middle of a fight (I would recommend 2 entropy and 2 devastation, creating +22 percent regen for both aimed shot and snap shot).
Aimed Shot:
Damage- Moderate
Recharge- Fast
Range- 80 ft
The big brother of Snap shot. This one has a bit longer animation time, but packs more punch. Using snap shot then aimed shot then snap shot again (it will be recharged when you are ready to shoot it), will allow you for a very nice 3 shot combination with no downtime between shots. This is nice for damage or for rapid fire situations (taking out lots of low health enemies).
Fistful of Arrows:
Damage- Moderate
Recharge- Moderate
Range- 40 ft (40 degree cone)
This is a gem for young archers. The fairly fast recharge and large cone allows for some impressive damage early on. Later on I decided to drop it from my build (to take snap shot / aimed shot combo).. but if you have room, I would recommend this. Great follow-up shot to use right after you fire rain of arrows, will hit right as rain of arrows is landing for its damage (boosting the area damage burst by 1/3 rd)
Blazing Arrow:
Damage- High
Recharge- Moderate
Range- 80 ft
This is a very nice power attack. Its a sniper level attack with a fire dot . Its animation time is a little long (so need to use it on monsters that will be alive long enough). Its a key power when bursting damage is important (great in pvp too ><
Aim:
Recharge: long
Its the only buildup type power we have. Take it, slot it with 3 recharge and use it before you do your area attacks (or for your blazing arrow / sniper shot to burst damage).
Explosive Arrow:
Damage: Moderate
Recharge: Long
Range: 80 ft (15 ft area damage around target)
This is a very nice power for the young archer. Its damage isnt huge, but it has added benefit of 30 percent knockback. Using Fistful of arrows and then explosive arrow allows for a 2 shot area combination (with aim) that can dish out some nice damage. It is also usable at caltropsed corners (use it on the first monster to show its face around the corner and fire it will hit his friends still out of line of sight).
Ranged Shot:
Damage: Extreme
Recharge: Long
Range: 120 ft
This is another very nice power. Its our sniper attack and can be interrupted but if you learn to use it wisely, its valuable. Its long range allows for pulling or for zapping running enemies (in pvp, shooting with blazing arrow and then starting a long animation ranged shot is a great combination, there is a delay before ranged shot hits so starting with ranged shot and then using blazing arrow can burst the damage pretty close together also).
Stunning Shot:
Damage: Minor
Recharge: Slow
Range: 70 ft
This is a nice control attack (disorient). Though it has a long animation time and keeps you from doing damage with new inventions, might be worth to take for the extra invention options. Its not my favorite, but I am more damage oriented (using this with taser will allow a double disorient letting to stop bosses, very handy in some situations if you go that way).
Rain of Arrows:
Damage: Extreme
Recharge: Long
Range: 60 ft (area attack around 20 feet of target location)
Congratulations! You are a true archer with this attack! Capable of decimating large groups of monsters. Its fast recharge means (once slotted) you can use it for each fight as you move with a large group (meaning you will be the one doing the majority of the damage over the course of the mission). This attack also has a VERY nice ability in the fact that it doesnt need line of sight to use (more on tactics of this later) worth taking, you need this! If you dont take it, you will make archers everywhere cry.
Devices
Web Grenate:
Range: 60 ft
Recharge: Fast
- Jump, - fly, - recharge, immobilize
Great for pvp, great for bringing down flyers. You are forced to take this, and comes in handy for immobilizing a monster thats chasing you (or running). Nice to toss around for the recharge against big monsters too (though the duration isnt the best)
Caltrops:
Damage: Minor (dot)
Range: 5-10 ft (20 ft area at target location)
Recharge: Long
VERY nice power. Its ability to stop entire groups of monsters in its tracks is perfect for keeping yourself safe. Any monsters that find themselves on caltrops will slowly run away (it has a slow component to it). The ways to use this are countless you can caltrops under a friend who is getting beat up, under yourself, at a corner to stop a group from coming around or chasing (And in PVP, great for stopping those stalkers assassin strike)
Taser:
Recharge: Moderate
Disorient melee attack. Not my favorite but you might like it for its disorient (can be used with stunning shot for a stacked disorient that will work on bosses).
Targeting Drone:
Recharge: Moderate
+per, +acc very nice power. With the natural accuracy bonus that archery gets, you will miss rarely once you have this (though, always nice to slot it with +to hit). The +per is handy and there is also a resistance to acc powers used on you while you have this.
Smoke Grenade:
Recharge: Long
-per, - acc nice ability if you have room for it. Can be used to sneak around troublesome monster groups or to get closer to drop a mine (I personally dont use it, more damage oriented).
Cloaking Device:
Recharge: Long
Stealth ability without a slow component in it (so you can move full speed). Very nice ability for the sneaky archer. Stacked with superspeed or invention stealth will allow you to have an invisibility level stealth (so you can plant mines at the feet of unnoticing monsters)
Trip Mine:
Damage: Extreme
Recharge: Long
Range: Point Blank Area (20 ft)
This is the key power to offset the problem areas of archery. Its amazing when soloing and setting traps (and even in groups). You can use this midfight in a group by setting it in the middle of the fighting (while the tanker distracts them). If a monster runs over it too quickly, it can avoid the blast (same with pvp). If the monster is very close to the center of the blast, it takes extra damage. (Also note that in pvp the enemy cant see these, area damage can hurt them and they will explode after taking a large amount of damage if you have mines planted and you die, the mines will all explode most likely taking out whatever killed you if you were standing close, hehe)
Time Bomb:
Damage: Extreme
Recharge: Very Long
Range: Point Blank Area (15 ft)
This is more powerful then trip mine, but has a much longer recharge and is set to detonate 15 seconds after you plant it (making it VERY hard to plan and use. Could be used in pulling situations if you set traps for a delayed charge).
Auto Turret
Damage: Minor (dot)
Range: 60 ft
Recharge: Very Long
This is a nice power for certain situations. It can be used to take the alpha strike when attacking a group of monsters, or can be set up for long fights (like AVs). Its fairly nice damage, but it has a huge endurance cost and a long activation time. I like to use it for even stronger trap ambushes and its nice that it will continue to fire even if you are held or sleeping (nice for a troublemaker stalker in pvp).
Note: It cant be moved, but once slotted it will be recharged by the time it poofs, with hasten you can have 2 at once.
Tactics!!
Ok, now that we got the basic abilities out of the way. Lets talk how to use them!
Basically, there are many many many different ways you can use the tools devices and archery gives you. This is why its my favorite set it allows more flexible play and depends on thinking ahead. The better you can plan the stronger and more dangerous you are.
Trap Setup-
Trap setup is key for a device user. The main issue is that monsters will normally be pulled in a line (so the first monster will run over your entire bomb setup, killing him but leaving his friends alive).
To avoid this, there are a few things you can do.
First: Pulling technique you need to pull out of line of sight from the monsters (to do this, run and jump around a corner while activating your area attack this will allow you to attack the group and pull without them attacking back and coming in a line). Once you have rain of arrows, you can use its ability to shoot without line of sight to pull groups very easily into your traps.
Second: Caltrops wall to keep the group of monsters from simply running past your mines and hurting you. You can set up your caltrops right behind the mines you have set. This will stop the entire bunch right at your mines for maximum damage.
Third: Insurance It is always a good idea to plan ahead, some bosses can slowly run past caltrops or fly over. This is why its nice to set another set of charges at the back end of the caltrops wall (so in a big fight, many are hurt in the initial blast and any left are again hit later on when they work past the caltrops or the caltrops disappear). It is also a good idea to set a mine where you will be hiding (around the corner) in case something sneaks around on you.
Trap Setup Scattered
This is a great way to set up traps in PVP. Setting them up in a minefield type pattern will reduce the chances that the enemy will simply run over them (not setting them off) and will let you have defenses in case more then 1 attacker comes.
Distance From Mines
This is a key issue to be aware of. Mines will not explode if its setter is too far away. This can be used to your advantage by setting a minefield and watching from a good distance. Once the group of enemies are on your minefield, you can go back into range and they will all explode at once (for pve and pvp).
PVP Burst
Using aim and then rain of arrows (from around a corner is nice so they dont notice you) on an enemy then get into line of sight and use blazing arrow and a follow-up ranged shot will allow for some very nice burst damage.
Turret Pulling
To do this, you need to stealth into turret range of the group of monsters. Set up several mines around the area where the turret will be and then set up the turret. It will start shooting right away and pull the monsters onto it (it has some nice defense and can survive abuse). Caltrops around the turret to keep them from meleeing it and as they charge, they will be hit by the mines.
This tactic is great for situations where you dont have a safe corner to rain of arrows or caltrops pull to.
Teleport Skip-
Set the mines in front and in back of a caltrops wall then pull the group into the first mines, teleport around to the back of the group and use your explosive arrow to send them over the caltrops and into the back mines.
Mid-combat mining-
This is great when lots are left and you have used up your rain of arrows. Just go into the middle of the fighting and plant your mines. Simple, yet I dont see many blasters doing this (the damage is worth it).
Teleport / Hover
This is just a little tip, with teleport and hover you will be able to teleport right into a big group and start planning your mines right away (instead of waiting for your teleport temporary hover to run out). Also allows for some quick movement sniper shots.
Mew