For more information on the amazon's passive/magic skills, please refer to the amazon's passive/magic skills section of the Arreat Summit.

These are the skills I term "active passives," skills that are cast, then (theoretically) forgotten. For the most part, this is true, though you should keep track of duration and, in the case of the decoy and valkyrie, making sure they're where you want them to be — if they're there at all.

Inner Sight (one point)

Clvl: 1
Prerequisites: None.
Effect: Illuminates monsters and decreases their ability to defend themselves.
Properties: 13.3 yard radius, fixed cost of 5 mana, casting speed is subject to faster cast rates.
Synergy from: None.
Synergy to: None.

Slow Missiles (one point)

Clvl: 12
Prerequisites: Inner Sight
Effect: Slows the missiles of nearby targets.
Properties: 13.3 yard radius, fixed cost of 5 mana, all ranged attacks slowed by 33%, casting speed is subject to faster cast rates.
Synergy from: None.
Synergy to: None.

Get in the habit of using these skills early. What makes them valuable is their ability to illuminate monsters but only one point should go into these skills, as extra points will merely lengthen their duration.

Let's start with Inner Sight: use it as much as you can, then as soon as you get Slow Missiles, forget about it. The extra DR reduction from Inner Sight isn't worth further investment because it's a straight value rather than a percentage, and slowing down missiles is much more useful as a defense than a mere DR reduction. Multiple castings of Inner Sight aren't stackable, they simply restart the clock. However, if two or more characters use Inner Sight on the same monster(s), it seems to reduce the monster's defense with each casting — the total reduction is the sum of the two reductions.

If something, anyone, anything is shooting at your bowazon, cast Slow Missiles. Period. Carriage return. Slow Missiles is the amazon's best multiplayer skill and your best friend in Hell difficulty, where ranged monsters are a dime a dozen; it has many uses, like shortening the speed and effective range of Inferno, charged bolts (such as those from LEBs), and spells cast by monsters. A high-level Slow Missiles is extremely effective to use against missile-dependent characters (like bowazons) in PvP; if you've a dueling character somewhere, keep something with a couple of Slow Missiles charges handy. It only helps, however, if your bowazon actually gets out of the way of the missile. This skill isn't stackable; multiple castings merely reset the skill's duration. Note that Slow Missiles changes the speed of the missiles, but not the attacker's rate of fire.

If either skill is chosen, having an assigned hot key is highly recommended.

Decoy (one to maximum)

Clvl: 24
Prerequisites: Inner Sight, Slow Missiles
Effect: Creates a duplicate image to distract targets.
Properties: Minion, casting speed is subject to faster cast rates.
Synergy from: None.
Synergy to: Valkyrie: +20% life/slvl.

The amazon uses Decoy the same way a modern-day sniper does: present the target with an easy target and pop its head off the second it shows itself. It is the oldest trick in the book, but I don't think enough players appreciate the value of Decoy after they gain Valkyrie. Let's go over the basics: decoy has 110% of your bowazon's maximum life, lasts for 10 seconds, and costs 19 mana to start; with every level, it gains another 10% of your bowazon's maximum life, lasts another 5 seconds, and costs progressively less mana per casting. At slvl-10, your decoy will have double your bowazon's maximum life for 55 seconds; at slvl-20, it rises up to triple your bowazon's life for 105 seconds. It has resistances and is able to dodge attacks. It can be cast repeatedly. Unlike other minions, allies cannot move through your decoy; monsters are attracted to your decoy even when you're standing in plain sight. It is more or less an low-cost immobile minion that stays exactly where you cast it: there are countless uses for this.

You should be experimenting with sniper/decoy tactics long after your bowazon gains valkyrie. Decoy is particularly handy in conjunction with Valkyrie and Slow Missiles; targets and tracking spells (like Guided Arrow and Bone Spirit) will home in on the first available target, which should be the decoy or valkyrie. It's also useful as a substitute valkyrie — you can cast a decoy in a spot, wait for your valkyrie to walk over to that spot, wait until her attention is occupied with monsters, then recast the decoy in a different spot.

— Joel Harrison

For example, suppose there are 30 targets rushing my valkyrie and bowazon. Fortunately, the 30 targets are broken into two manageable groups of 15 apiece, with group A coming in from the 2 o'clock position and group B coming in from the 6 o'clock position. (Look at a watch and you'll have a decent idea where this is going.) My bowie is going to run to the 9-12 position to Strafe, Freeze and Immolation Arrow, but I can't rely on my valkyrie to hold the attention of 30 targets at once (either the valkyrie is going to move when I don't want her or some of them will start looking for other targets…like my bowazon), so I pop a decoy at 3-5, diverting some monsters from my valkyrie. So we've now prevented one large group from being a hazard to my valkyrie and we want this to happen, whether my valkyrie has 1,000 or 5,000 life; though only 8 targets can surround her at once, a lot of targets in Hell have attack ranges of 2 or greater, meaning that my valkyrie will be set upon by more than 8 targets, perhaps 10 or even 15 at once. However, by using repeated castings of decoy, I not only prolong the life span of my valkyrie, but control the spacing of battle by luring monsters as far or close to my valkyrie as I please.

This tactic can be expanded upon with hirelings in LOD, but note that they while they have many virtues, greater durability than your minions is not one of them. They also tend to not be exactly where you want them.

Consider also that a decoy is invaluable as a portable shield against ranged attacks: it doesn't move, it has high priority for monster attack AI, and it's cheap. Despite its importance, not too many points should go into Decoy, not until you're done developing your other skills — unless, of course, you want to beef up your valkyrie. Generally, you want to aim for a balance between life and duration.

Another place that a decoy comes in handy is the Worldstone Keep, where Baal has the annoying tendency to launch an elemental attack at anything that stands still for more than a few seconds. The catch is that Baal can only target one thing at a time, so a long-lasting decoy can be a boon if it's left in the right place (which is hopefully, far, far, away from your bowazon).

Giving Decoy an assigned hot key is highly recommended.

Valkyrie (five to maximum)

Clvl: 30
Prerequisites: Dodge, Inner Sight, Avoid, Slow Missiles, Evade, Decoy
Effect: Summons a powerful valkyrie warrior to fight by your side.
Properties: Minion, life scales with difficulty level, casting speed is subject to faster cast rates, uses magical equipment with attributes of a level equal to (25 + 3{slvl}).
Spell Timer: 6 seconds.
Synergy from: Decoy: +20% life/slvl, Penetrate: +40 AR/slvl, Critical Strike: as per skill description, Dodge: as per skill description, Avoid: as per skill description, Evade: as per skill description.
Synergy to: None.

The valkyrie represents one of the most drastic changes to the amazon class as a whole, so read carefully. The valkyrie ends most vulnerability problems a bowazon will have with tougher targets by granting her a remote shield. The valkyrie is a bowazon's most useful skill, but I've learned to not rely on her to protect my bowazon all the time, but to use her in conjunction with my hireling, Slow Missiles, and Decoy. There is no excuse to not have a valkyrie: regardless of what kind of amazon you play, even a single point in Valkyrie is a point well spent. A quick look at her synergies should give an astute viewer a good idea of what kind of potential this minion has: imagine a high-level spearazon with 3,000-5,000 life and your bowazon's base passive skills packing sacred armor and a war pike, and that's what a valkyrie is. Along with the clay golem and shadow master, the valkyrie sits in the enviable position of being one of the best minions in the game.

Point investment depends purely on personal preference; my personal preference is a high-level valkyrie. In the past, valks were often resummoned for repositioning or to quickly use them as an animated shield, so it isn't necessary to maximize her effectiveness at the cost of skill points. I used to recommend basing her skill point usage on recasting rationale: if she died in combat too often, then consider adding another point to increase her life. If she's never where you need her to be, then don't add points to keep her mana cost low. In addition, her life scaled with the number of player in the party, so a valkyrie was eight times tougher in a full game — this is no longer the case now. Thus, a valkyrie between 5-10 points was a good balance between life and mana cost — this was further complicated in v1.10 by the valkyrie's casting timer: it's six seconds. Fortunately, this is balanced out with her vastly improved fighting abilities. For low to medium-offense builds, the valkyrie as an actual combat unit warrants some attention.

Let's start with durability. Valkyrie life scales proportionately with her mana cost; it also scales with difficulty level (as noted by Chippydip). In short, the tougher you want your valkyrie to be, the more points you invest in Valkyrie, Decoy, or both. It's just that simple; what's not simple is balancing out your bowazon's defense via valkyrie with her offensive potential and your bowazon's offensive skills (which is taken care of on a case-by-case basis). Another reason to invest in your valkyrie is to upgrade her items, which brings to attention to ability to actually kill things, something she's never been able to do before.

When a valkyrie is summoned, she automatically receives weapons and armor. These items receive attributes of a level equal to (25 + 3{slvl}), so a slvl-5 valkyrie will be using a clvl-40 spear. As of v1.10, the valkyrie can spawn with…

— Fuzzbox

…with many thanks to Fuzzbox, adeyke, and HunkyDory, who found this all out. According to Ruvanal, valks don't get any new types of equipment after slvl-27. Unless listed otherwise, all equipment is magical.

Like all minions, a valkyrie takes extra damage from Andariel, Duriel, Mephisto, Diablo, and Baal. A hot key for valkyrie is highly recommended. For your information, I named my valkyrie "Lenneth."